# KRE High Ports?



## Norms68 (Jul 17, 2013)

Still building my 461 stroker and a friend of mine who is an engine builder says I should go with the KRE High Ports.

These heads will be the 80cc chamber and flows 330cfm.

This will push me into about 11:1 compression ratio. I know that's past the sweet spot of 10.5:1 for aluminum but it's tempting.

Anyone use these heads or run this compression ratio on pump gas?

Thanks for any input.
-Norm


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## Chris-Austria (Dec 23, 2010)

I had to decide if I want Kre or E-heads as well. I choose Edelbrock because I found many people who prefer them. I was told that Kre won't flow what they claim.. but I have no test results.
This is an article I read a year ago when I searched the internet about Kre: Serious Pontiac Horespower - Rock and Roll Engineering

93oct or more is necessary, maybe you should mix it if you cannot get more than 93 at the gas station.

If you don't plan on using a very radical camshaft I think a little less SCR would be nice. Bigger chambers or dished pistons would be my choice.


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## Bensjammin66 (May 12, 2009)

This isnt the average discussion of KRE vs Edelbrock though Chris, the KRE High Ports are in a leaugue of their own @ 330cfm stock and can be opened up to 400+ if you got a bottom end that'll turn 7500rpm. Norm, your best bet is to email Jeff @ Kaufman Racing and ask his advice, Dave @ SD Performance would be a brain to pick as well but I always hate pestering guys at machine shops for advice if im not spending money there so i'd email Jeff first. 

Side note: I run the regular KRE D-ports with a 290cfm port job @ 10.75:1 compression with 93 octane and have zero detonation issues with 32 degrees total timing


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## Norms68 (Jul 17, 2013)

Also saw an interesting article here about Dynamic Compression Ratio (DCR)

Dynamic CR

I'll be using the math to find the right head / cam combo. I'd like to go big on cam but it looks like staying under 8.25 DCR is the key to detonation free motoring.

-Norm


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## BearGFR (Aug 25, 2008)

I'm aware of the whole static compression ratio (SCR) vs. dynamic compression ratio (DCR) debate. For awhile, the idea that DCR was what really mattered made sense to me, but I'm not so sure any more. Here's why:
SCR uses the full stroke length in the calculation and assumes that compression begins as soon as the piston moves away from BDC. DCR attempts to take into account that the intake valve is still open at this point and posits that compression cannot possibly begin until the intake valve closes, so the DCR calculation takes the intake closing event as the point when compression begins (which means we're using effectively a shorter stroke in the calculation). That makes sense to me, or it did for awhile. There's one very important concept that this idea leaves out: detonation occurs when CYLINDER PRESSURE is on the compression stroke is too high for the fuel being used. The engine doesn't care about any "ratio" or how it was calculated, all it cares about is raw cylinder pressure. The whole "DCR" approach leaves out something very important: that the air in the intake charge is moving, and further - as rpm increases the air is moving faster too. The whole assertion that "compression cannot begin until the intake valve closes" is, simply put, horse hockey. Wanna prove it? Take a piece of PVC pipe, cap off one end, put a pressure gauge at that end, then position the open end a couple inches away from your face and blow into it. Can you make the gauge move? Yes you can. Does that mean pressure has increased inside the pipe even though the end of it was still open? Yes it does. Why did the pressure increase? Because you made the air _move_ and because it was moving (and has mass), it had intertia, and because it had inertia, it started to "pile up" inside the closed end of the open tube... viola - pressure increased. Kinda "blows" holes in the idea that cylinder pressure can't start to increase before the intake valve closes, now doesn't it. In fact, the whole point of putting a different cam in an engine is to take advantage of the inertia of the moving air column in the intake tract so that things are "timed" to allow that moving air to flow into the cylinder and start filling/pressurizing it as soon as the valve opens, at the rpm the cam is "tuned" to operate at most efficiently.

So. What matters is CYLINDER PRESSURE - not either of the two calculated ratios, and CYLINDER PRESSURE (which as far as I know can't be directly accurately measured in a running engine at rpm, at least not by us mere mortals) is influenced by all kinds of things: cam timing, rpm, air flow velocity, port shape, port cross-sectional area, air temperature, intake manifold, restrictions in the air flow (carburetor) - just to name a few. That's why using either SCR or DCR to build an engine is AT BEST just an approximation of how things are going to turn out, detonation-wise, in the finished build. The wise engine builder knows this, and will adjust accordingly. On a street engine that has to perform and stay together under a wide range of conditions, he'll design in an adequate safety margin and won't try to push compression (either "kind") right to the limit. In a race-only engine that has to run in a much narrower set of conditions and operational modes, doesn't have the same requirements for longevity, and where every scrap of power matters, one might push things a little closer to the edge.

Anyway, them's my thoughts --- for whatever they might be worth. 

Bear

Oh, and another thing that might be making late-intake closing, long duration cams _appear_ to let engines work at higher compression could be this: Time. A late intake, long duration cam is going to shift the point of peak volumetric efficiency (peak cylinder pressure) to a higher rpm. The further away we are from peak VE rpm, the lower cylinder pressure is going to be because volumetric efficiency is down - we aren't doing a very good job of filling the cylinders with air. As pressure rises in the cylinder even at peak VE rpm, it takes time for the fuel to absorb the heat coming from the increased pressure. As rpm goes up, there is simply less time for the fuel to heat up and detonate before being lit by the spark plug.


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## Chris-Austria (Dec 23, 2010)

Wow, that's very informative. (had to read it twice)
I have read a lot about SCR and DCR but no one could explain it that way.
Sorry I didn't know the High Ports from KRE, I was thinking of the regular ones. I would still want them to prove the cfm ratings


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## leeklm (Mar 11, 2012)

I sprung for a set of KRE 295's from SD. Whether edelbrock or KRE, I personally think it is worth spending just a few more dollars to have a reputable shop "work" the heads for you so that they should be flowing as advertised. If they were not, shops like SD would get a bad rap in a real hurry.

FWIW, Dave at SD prefers the KRE over Edelbrock. Nothing bad to say, but said many guys go with edel just for the name. Maybe he makes better profit margin on the KRE's  Regardless, I am looking forward to the new heads and roller cam to get this engine done "right" once and for all!

For comparison, a dport e-head from summit racing is $1,150 /free shipping, while the KRE 295 from SD is $1,237 + shipping. For that difference, I am thinking the KRE is better bang for my dollar. Now, if I go to sell these heads later to a non-pontiac buyer (i.e. the casual observer), the e-heads would likely sell for more than the KRE due to name recognition IMO.


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## BearGFR (Aug 25, 2008)

I like the chambers on the KRE's better than the ones on the round-port E-heads, but since my car was already set up for round ports (exhaust system) I went with the latter. You're right though, "out of the box" none of them make a significant difference. They need some TLC from someone who really knows what they're doing in order to wake them up.

Bear


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## Norms68 (Jul 17, 2013)

I'll have to do some more research, good points. My buddy said the intake runner wasn't enough on the 295's. The runner is 197cc and he was suggesting 220 or above.

If I do go with KRE High Port I can run the .060" gasket and bring CR down to 10.7:1

Do you run into any problems with thicker gasket? 
I think I can be comfortable with 10.7:1 CR.

-Norm


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## ALKYGTO (Mar 29, 2010)

Did they recommend a header for these? I just have to wonder about fitment with a "high port" head knowing that headers are a pita on these cars in the first place. Just curious :cheers.


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## Norms68 (Jul 17, 2013)

I think I wanna stick to the Ram Air Resto exhaust manifolds just to keep away from the header problems. I'm not trying to get every once of power anyway.

I'll find out when I call.
-Norm


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## leeklm (Mar 11, 2012)

Norms68 said:


> I think I wanna stick to the Ram Air Resto exhaust manifolds just to keep away from the header problems. I'm not trying to get every once of power anyway.
> 
> I'll find out when I call.
> -Norm


The RAM AIR manifolds will make your life a little easier, and you will likely swear at your car a lot less. probably kick the dog or cat less as well when you go back into the house after working on the car. There is a point where headers will make considerably more power, but the RAM AIR manifolds do a really nice job for a street car, and will lose very little hp with many combos.


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## ALKYGTO (Mar 29, 2010)

leeklm said:


> The RAM AIR manifolds will make your life a little easier, and you will likely swear at your car a lot less. probably kick the dog or cat less as well when you go back into the house after working on the car. There is a point where headers will make considerably more power, but the RAM AIR manifolds do a really nice job for a street car, and will lose very little hp with many combos.


Just seems redundant to run a high flow head through exhaust manifolds :confused. 

I've seen dyno tests where the RA pieces did an adaquite job compared to the non RA logs but were still down on power compared to a tube header. And that was on iron D port heads which don't flow nearly as well.

I understand the dilemma here with wanting a maintenance free exhaust system but just wondering why spend all the money on trick heads when you are going to choke them back with manifolds? 

* What is the most HP anyone has ever made with RA manifolds on a NA Pontiac engine?* I'd _really_ like to see this.


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## Bensjammin66 (May 12, 2009)

Norms68 said:


> I'll have to do some more research, good points. My buddy said the intake runner wasn't enough on the 295's. The runner is 197cc and he was suggesting 220 or above.
> 
> If I do go with KRE High Port I can run the .060" gasket and bring CR down to 10.7:1
> 
> ...


Do some more reading on this.. By no means am I an engine expert by any stretch of the imagination, but i think bigger intake runners means they "wake up" and become efficient at a higher rpm instead of on the bottom end for more street cruising. Though judging by the numbers on the heads you are considering you are going for top end (3500-7500rpm) anyway. Dave @ SD mostly recommends the KREs for street cars for the smaller intake runners but also chamber design, spark plug location, etc.. High ports are a leaugue of their own though. I take it this is a race car?


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## Bensjammin66 (May 12, 2009)

ALKYGTO said:


> I understand the dilemma here with wanting a maintenance free exhaust system but just wondering why spend all the money on trick heads when you are going to choke them back with manifolds?
> 
> * What is the most HP anyone has ever made with RA manifolds on a NA Pontiac engine?* I'd _really_ like to see this.


:agree

Pain in the ass as installing headers is, i cant imagine dropping $2,500+ on heads and running them with ram air manifolds. For a few hundred dollars more you can have a set of headers that'll make, man i gotta guess 20 to maybe 40 more hp over manifolds. At least from a head that inhales 330+cfm stock.


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## leeklm (Mar 11, 2012)

Here is an example from the SD site. ...
In a recent dyno test this cam installed in a 468ci engine with 9.5 to 1 compression, a set of our 260+cfm 6X heads, fully prepped cast iron Q-jet intake and a prepped Q-jet made 485+hp and 560+ lb/ft of torque on 91 octane.

The further claim was virtually no difference with ra manifold or headers. Now these are iron heads flowing 260+, not quite as good as the 295, but closer. A higher rpm cam would likely prefer the headers.

For me, I did not want to dump more time and dollars into porting iron heads, etc. With the kre, I get a superior design, good flow & power (even with ra manifold) new springs matched to my roller cam etc. Dumping another 1k or so in the iron heads felt like chasing my tail. The kre will now take anything I choose to throw at it. Those who have seen my posts over the past couple of years know I cannot ever leave things alone 

In hindsight, I should have started with the KRE or e-head from day one, and not dumped any money into my iron heads. Same goes for my upcoming roller cam. It took two failed attempts at a flat tappet cam to learn that lesson, although 3 times might be a charm...


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## Norms68 (Jul 17, 2013)

No it's not a race car, just for street use.

The KRE D-ports and High Ports are only about $200 difference. I'm just trying to get the most bang for the buck. Either way I'm using ram air manifolds so with that being said minus 20-40 hp either head. The difference though is 20-40 from 500+hp or 20-40 from about 600+hp head. If I do high ports I'll still come out on top better than the other.
-Norm


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## Bensjammin66 (May 12, 2009)

Norms68 said:


> No it's not a race car, just for street use.
> 
> The KRE D-ports and High Ports are only about $200 difference. I'm just trying to get the most bang for the buck. Either way I'm using ram air manifolds so with that being said minus 20-40 hp either head. The difference though is 20-40 from 500+hp or 20-40 from about 600+hp head. If I do high ports I'll still come out on top better than the other.
> -Norm


*Once again I am no expert and a call to Jeff Kaufman or Dave @ SD is your best bet* but for a street driven car I dont think the high ports are the way to go. I know it seems tempting cause theyre seemingly only a few dollars more than D-ports but that appears to be a race head. Bigger isnt always better in our case where we street drive our cars. With the high ports large intake runners and shear volume those heads like to maintain 3500rpm+ to be utilized for their potential. 

There are formulas all over the web, but if im not mistaken for a head to utilize 330cfm on a 461ci motor, it needs to turn like 7500+rpm! Even if you do have a bottom end that enjoys that sort of rpm, you will not encounter very friendly law enforcement if caught pushing your motor to its potential. 

IMO, the smaller intake runners on a ported set of D-port KREs matched to a roller cam would suit you better. Good vaccuum and a great idle from the cam, super strong low end and cruising signal/responce from the heads and still 550hp with the right carb like an AED850HO. Deduct say 25hp from the manifolds and you got a 525hp street motor built for 1500-6000rpm. With good traction in a 3400lb car you should flirt with low 12s / high 11s easily.

My brothers '68 Coronet race car stages at 3500 then gets shifted around 7000rpm and turns 10.70s consistantly with ported, large runner Indy cylinder heads. Impressive for sure. But with his motor and convertor hating anything under 4000rpm its useless even going for a spin around the block. My .02 is build a 500-550hp combo for what your primarily doing. Street driving.


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## Bensjammin66 (May 12, 2009)

This is at 100% engine efficiency, 7,462rpm for max horsepower from a 330cfm head! Thats a race car. If 525-550hp isnt enough and you MUST have 600+hp ( which i can completely understand lol ) I always suggest people find it other places than high compression and high rpm race parts. Race gas is a hassle and is expensive and no one reguarly drives 7,500rpm on the street. An 80+mm turbo or centrifugal super charger first come to mind if you didnt buy pistons yet... The saga continues and the wallet gets lighter lol, good luck with the build! 

Your RPM at HP is 7,462.15 computed from your 
Cylinder Head Flow of 330 at 28 inches and CID of 461 inches

Max RPM from Head Flow Calculator


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## Norms68 (Jul 17, 2013)

Talked with Jeff Kaufman,

He says I can either do the 310cfm d ports or the high ports. He suggests either with the northwind intake and 1000 cfm 4150.

Referring to the conversation about the high rpm I believe for me the 310cfm d ports would work for my build. 

Thanks for all the input and I'll share the out come of my build.
-Norm


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## BearGFR (Aug 25, 2008)

Keep in mind too that the comments elsewhere about it being possible for an exhaust system to be too big also apply to heads. There's a reason you don't find monster heads like Tigers and CV-1's on street cars. Yeah, they flow over 400 cfm but you've also got to think about flow velocity. In anything but racing conditions, they'd be hideously difficult to run and tune. You'd have all kinds of reversion problems, etc.

Bear


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## geeteeohguy (Feb 2, 2008)

I have not read every post on this thread, but I did pick up the fact that this car is going to be a street car, and that the OP wants to run high port heads. My take: high port heads make more power at high rpm and are for racing. They have less velocity at lower, street rpms than the standard port heads. In other words, your engine will scream at 6000-7000 rpm, but be saggy and sluggish below 4000 or 5000 rpm. Inferior in throttle response off idle, fuel economy, and all around drivability on the street. So, for a bracket racer, high ports are great. Or maybe for a 535 on up CID mill. But for the street, they'd be my personal LAST choice. Higher flow=higher HP @ higher RPM's. It's TORQUE that moves the car off the line, not top end HP. Anyway, just my thoughts, and I am not a head guru or an engineer. Just a GTO guy.


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## Norms68 (Jul 17, 2013)

*Which cam now?*

Yeah pretty much steering away from the high ports now.

Jeff Kaufman suggests d ports 310cfm with northwind intake and 1000cfm 4150.

*My next and final question of my build is the cam. Looking at going with a hydroboost system. So... what would be the optimal hyd roller cam?*

*Recap:* 68 GTO 461 build, auto trans, street use, pump gas. Butler rotating assy, flat top pistons, 4.155 bore, 4.25 stroke, 6.8 rods. 80psi oil pump, rear oil plug drilled for oiling dist gear. Kre d port heads ported 310cfm setup for hyd roller, port matched northwind intake, 1000cfm 4150. Static compression ratio 10.6:1 ram air resto manifolds, 2 1/2 pypes to race ready exhaust.

Did I miss anything? Thanks for any cam suggestions!

-Norm


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## Instg8ter (Sep 28, 2010)

I'd see what Bears running, similar build cept he's running solid roller i think and that car screams


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## BearGFR (Aug 25, 2008)

I am indeed running a solid roller. Two reasons I went that route initially:
1) Roller lobe profiles mean more duration without more overlap (idle vacuum, street manners)
2) Solids are lighter than hydraulics, so I don't need super agressive springs.

Since then, add to the list the fact that rollers don't need tons of ZDDP to live.

If you look at the "advertised" duration specs on my cam, it's not even as agressive as the factory specs for the Ram Air IV. However if you look at the area under the lift curve, I've actually got more because of the steeper ramps of the roller lobe profile.

In a street car, the limiting factors on "rowdiness" will tend to be things that need idle vacuum like power brakes, factory HVAC valves, etc. My cam idles at about 12" to 13" once it's warm, but even with that I opted to take the safe route and went with Hydroboost brakes and replaced the factory a/c with an aftermarket one. That way if I ever decide to step up to a cam with more duration, I'll already be set.

Also be aware that Northwind intake is a single plane so it works better at higher rpm than at lower - meaning it's going to cost you some bottom end torque. However, with a big 461 that's not necessarily a bad thing. Your tires will thank you.  I'm running a single plane (original Torker) on my car and I still can't just hammer it from a stop on the street, even with the Nitto drag radials on. I've got to roll into the throttle from about 5-10 mph. And I'm only packing 800cfm.

Bear


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## Norms68 (Jul 17, 2013)

Bear, are you still running this?

Custom grind Comp Cams Mech Roller; .377/.381" lobe lift
Duration at .050 in 236/242 degrees
Advertised Duration 273/279 @ .015" lobe lift
Lift w/ Rocker Arms .622/.628" (1.65 ratio)
Lobe Separation Angle 110
Installed Position 106 degrees inline center line

I would like to burn some tires from a stop if I wanted to and I do like power a little bit lower in the band. Basically need a setup that can rip a rice burner if needed. Thank again for any advice.

-Norm


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## BearGFR (Aug 25, 2008)

Norms68 said:


> Bear, are you still running this?
> 
> Custom grind Comp Cams Mech Roller; .377/.381" lobe lift
> Duration at .050 in 236/242 degrees
> ...


Yep, that's the one.

Note - when converting to a mechanical cam, Jim recommends installing oil restrictors into all the lifter bore oil feel passages. I did mine myself.


















































(On the last photo, something about the camera angle makes it look like the restrictor is sticking out of the hole and the edges of the hole look burred... but that's all just an illusion - otherwise the lifter wouldn't even fit into the bore, and if it did, it sure wouldn't live long. )

Bear


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## Norms68 (Jul 17, 2013)

Is that for hyd roller as well or just the solid roller?

-Norm


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## BearGFR (Aug 25, 2008)

Solid/mechanical *ONLY* :willy:

It doesn't take much oil to lubricate the lifter bores, but hydraulics need the oil supply to function correctly.

The logic here is that since the solids (roller or flat) don't need the extra oil, the restrictors will keep more of it down where it will do some good: the mains and rods.

Bear


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## Norms68 (Jul 17, 2013)

Ok, gotcha. Still learning as I go :willy:

-Norm


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## BearGFR (Aug 25, 2008)

Ain't it fun? I just love this stuff. I hope we get our house sold and get moved out to the new place soon... I'm starting to get the bug again to go build something. 

Bear


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## geeteeohguy (Feb 2, 2008)

Bear, I'm still trying to find you a likely '65!!!


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## Instg8ter (Sep 28, 2010)

Yeah i have a few open bays in the new shop. Was unable to get the heat and new elec. service in before Detroit turned into the North Pole for 3 months, but as soon as it gets thawed out I have a 91' fox body mustangs that needs assembly. Then i might try and talk the neighbor out of his 70' GTO that just needs finish bodywork and paint. In order to get that by the boss i will have to cough up a down payment for her new CTS, still trying to talk her into the V.


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## Norms68 (Jul 17, 2013)

BearGFR said:


> I'm running a single plane (original Torker) on my car and I still can't just hammer it from a stop on the street, even with the Nitto drag radials on. I've got to roll into the throttle from about 5-10 mph. And I'm only packing 800cfm.
> 
> Bear


Bear,

You can't hammer it because? Burn your tires off? Bogs down from stop?

Sorry just didn't quite understand why. Thanks.

-Norm


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## BearGFR (Aug 25, 2008)

Hey Norm,

No - no boggies here. If I hammer this thing from a stop on plain old street pavement, it just blows the tires off - even with the drag radials. About the only place I can get away with doing that is on a prepped track.

Bear


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## Norms68 (Jul 17, 2013)

Lol, that's what I thought but just wanted to make sure. :cheers I think that's why my buddy is also suggesting the single plane intake.

What stall you running? I think I need about 2800 for my setup.

-Norm


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## BearGFR (Aug 25, 2008)

Mine is in the neighborhood of 3000-3200. If I had it to do again (and maybe I will someday) I wouldn't go that high. Even though 3200 is right in the "fat" part of my torque curve (that's how you want to choose a stall speed for racing) it introduces other issues. The main one being heat. Anywhere under stall speed the converter is "slipping" and that puts a lot of heat into the transmission fluid. Heat (and fire) bad. :willy:

So, if I were to put an overdrive into this thing in order to improve highway manners for long trips, as it is the converter would always be slipping -- not good -- so I'm kinda stuck where I am for now.

If I were to do it all again (and had the cash to do it) then I'd go with a 4L80E beefed up enough to handle the torque, and running a converter with a "lock up" circuit. That'd give me the best of both worlds: Strong and a stall appropriate for racing, but overdrive and controlled lockup for highway.

Bear


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## geeteeohguy (Feb 2, 2008)

I agree with the lock up torque converter. Virtually NO heat driving down the road locked up, due to no slippage. Better MPG all the way around, too. But extra gears cost extra $$$!!


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## Bensjammin66 (May 12, 2009)

Norms68 said:


> I would like to burn some tires from a stop if I wanted to and I do like power a little bit lower in the band. Basically need a setup that can rip a rice burner if needed. Thank again for any advice.
> 
> -Norm


I love this.. Norm, you will absolutly melt tires onto the pavement with a combo like this not just burn them! My old 468 with stock 6x's and a HFT cam would roast tires from a stop with 3.73s and limited slip. 
Recently I assembled a combo like you are talking about but i used 290cfm KREs and the "old faithful" hydro roller from SD, topped with an 850AED. The combo youre talkin about will like a little higher rpm than mine but my guess is you are approaching an easy 600hp with 310cfm heads and the dominator. Yah, youre gonna roast some tires. 

:cryin: Ive never hated winter more in my life than right now cause its turn key ready to go. Like you, I cannot wait to test this thing out. 

Glad to see you axed the race heads.. Good move! Keep us posted on your decisions for the valvetrain and how the build goes overall!

On a side note: Did you have issue with the windage tray? I noticed you said 6.8" rods so those are BBCs on a stroker crank right? I ask cause my Eagle 6.625s hit the windage tray and had to modify the BOP 3/4 length to clear the arp bolt heads


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## Norms68 (Jul 17, 2013)

Bensjammin66 said:


> On a side note: Did you have issue with the windage tray? I noticed you said 6.8" rods so those are BBCs on a stroker crank right? I ask cause my Eagle 6.625s hit the windage tray and had to modify the BOP 3/4 length to clear the arp bolt heads


I got the 4.25" stroker kit from Butler Performance. 6.8" forged eagle rods. I ended up opting out of the windage tray. I got a baffled oil pan to help with windage and tapped the #3 cap to hold my lower dipstick tube. It'll take a little away from power but the baffled oil pan should help keep a lot of it down.

-Norm


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