[Felix C]

See mostly 5500rpm. Anyone go higher? What top end and bottom end combo are you using?
hydraulic roller camshaft?
Dual plane?
cylinder heads?
Connecting rod and piston info?

400s or better said 3.75" stroke and 4.121" bore minimum only please.

[Rodney R]

The fastest I've spun my 400 to was 6300. I didn't realize it was spinning that fast at the time and will keep it at under 6k from now on, but I know I could get more out of it if I had put a better bottom end in it. I conditioned and peened a set of factory rods and have a nodular crank in the motor with TRW pistons. See my signature for more info on the motor.

[PunchT37]

I don`t spin engines higher than they make power. I built a 400 PWH engine for a buddies `79 T/A. Stock bottom end. Stock heads with a 60241 Crower cam. I could tell the engine quit pulling after 5200 or so. I twisted it to 5500 a few times. You could tell it wasn`t happy at all there.

I have a 455 with stock rods and TRW pistons also. Larger cam and ported heads. I turn that thing to 5700 to 6000 ALL the time. But, it makes power there also.

So, it`s about the ability to make power at the shift point, then, it will be about the parts strength later. No use building a 7000 rpm capable top end and using stock rods.

I wouldn`t have a problem spinning a 400 with stock rods to 6000 to 6200 or so IF I could make power there.


Aftermarket parts? 7000 to 7500 wouldn`t be a problem for me. We used to turn a 428 with rubber rods to 7000 for years. Guess we were lucky.

[gto406]

In my '69 Bird, the 406 Pontiac - was spun up to 6300 RPM on the dyno (hp was steady/strong at that RPM according to my engine builder). However, the bottom end has had some work done to it (mag'd and shot-peened/polished rods, ARP rod-bolts, a bit of work to the crankshaft, etc., etc.). I likely won't spin it any higher than 6100 RPM. This will eventually be more of a race car (once my GTO is back together) with occasional street use.

For my '72 GTO the rotating assembly is mostly stock (ARP rod bolts, stock crank). I keep a 5800 RPM chip in the MSD - and I believe it bounced off the limiter (once) at the track. This will be a street car (going forward). I won't be tracking this car anymore (unless it is to go through a road-course).

[Felix C]

Originally Posted by gto406

In my '69 Bird, the 406 Pontiac - was spun up to 6300 RPM on the dyno (hp was steady/strong at that RPM according to my engine builder). However, the bottom end has had some work done to it (mag'd and shot-peened/polished rods, ARP rod-bolts, a bit of work to the crankshaft, etc., etc.). I likely won't spin it any higher than 6100 RPM. This will eventually be more of a race car (once my GTO is back together) with occasional street use.

For my '72 GTO the rotating assembly is mostly stock (ARP rod bolts, stock crank). I keep a 5800 RPM chip in the MSD - and I believe it bounced off the limiter (once) at the track. This will be a street car (going forward). I won't be tracking this car anymore (unless it is to go through a road-course).

If you do not mind, what camshaft/intake/head combo on the 1969 Firebird to make hp at 6100-6300rpm? I presume you head long tube headers in place?

[Tom Vaught]

I ran a RAV 400 Crank for a while with good SD Rods to 7200 with a 255/265 Comp solid flat camshaft and a 850 CFM carb. Custom modded Edelbrock "Don Kennedy style Torquer-1" (Dual Rear Runner sections welded together) with a custom Spacer.
PAC Springs.

Block was my original 64 389 GTO block bored out to a 4.125" bore size. 11.55-117 mph

Tom Vaught

[Rodney R]

Originally Posted by PunchT37

I don`t spin engines higher than they make power. I built a 400 PWH engine for a buddies `79 T/A. Stock bottom end. Stock heads with a 60241 Crower cam. I could tell the engine quit pulling after 5200 or so. I twisted it to 5500 a few times. You could tell it wasn`t happy at all there.

I have a 455 with stock rods and TRW pistons also. Larger cam and ported heads. I turn that thing to 5700 to 6000 ALL the time. But, it makes power there also.

So, it`s about the ability to make power at the shift point, then, it will be about the parts strength later. No use building a 7000 rpm capable top end and using stock rods.

I wouldn`t have a problem spinning a 400 with stock rods to 6000 to 6200 or so IF I could make power there.


Aftermarket parts? 7000 to 7500 wouldn`t be a problem for me. We used to turn a 428 with rubber rods to 7000 for years. Guess we were lucky.

+1. I had a 455 in the car with a smaller comp cam and the car only made power to like 4800. With the HR camshaft that I have in the car now on a 112 LSA and ported heads, the motor will pull really hard at 6300rpms, but I didn't want to destroy the bottom end so I kept it there.

[72LuxuryLeMansLa.]

Originally Posted by PunchT37

I don`t spin engines higher than they make power. I built a 400 PWH engine for a buddies `79 T/A. Stock bottom end. Stock heads with a 60241 Crower cam. I could tell the engine quit pulling after 5200 or so. I twisted it to 5500 a few times. You could tell it wasn`t happy at all there.

I have a 455 with stock rods and TRW pistons also. Larger cam and ported heads. I turn that thing to 5700 to 6000 ALL the time. But, it makes power there also.

So, it`s about the ability to make power at the shift point, then, it will be about the parts strength later. No use building a 7000 rpm capable top end and using stock rods.

I wouldn`t have a problem spinning a 400 with stock rods to 6000 to 6200 or so IF I could make power there.


Aftermarket parts? 7000 to 7500 wouldn`t be a problem for me. We used to turn a 428 with rubber rods to 7000 for years. Guess we were lucky.

Punch,
Isn't the valve train usually the limiting factor? I was taught that if the iron or steel parts are strong enough, ie forged, the whole problem would be keeping control of the valves. As long as the heads are set up correctly so that the valves are under control, not bouncing off the seats or floating, all is well. Is this correct?

Karl

[tom s]

I have found with back to back dyno testing the dual plane intake is the choke.Even with enough cam a engine setup to make HP to lets say 6800,put a single carb dual plane it might give up at 5800.Put a spcer on it and then maybe 6000,etc.Tom

[old66tiger]

Forged crank, rods and light pistons, I have my rev limiter set to 6500, shifing at 6300 or so. With the hyd roller and solid lifters, it pulls like a freight train on acid all of the way to shift point. In most instances, it revs so quick, it is hard to keep if off the rev limiter.

[gto406]

Originally Posted by Felix C

If you do not mind, what camshaft/intake/head combo on the 1969 Firebird to make hp at 6100-6300rpm? I presume you head long tube headers in place?

Hi RodneyR,

The cam was/is a CompCams P280-H (480/480 lift at .050). I had it at the engine builder due to wiping the original CompCams custom hyd-grind (which was over 520 lift on the intake). The heads were heavily ported #13's (by potentpontiac) which were re-done by the builder with Ferrea valves, a brass valve-seat and a cut (forgot how many angle's he put in the valves). Intake is a port-matched KRE Northwind (with a separate cross-over fabricated up). Right now, given the car has the stock inner fenders, I am using the Hedman 3-tube headers on it. Not sure those would be long tubes.

The engine builder ran it on the dyno with his headers (not sure what they were). Car made 420hp @6300 RPM and 458 ft-lbs of torque at about 4500 RPM.

I am sure if I went hyd-roller (and above 500 lift) the motor will really wake up. However, it is a great street car (enough rumble/grunt) to enjoy. Have not baselined it yet.

A quick video of my car running

Cheers,
Brian.

[PunchT37]

Originally Posted by 72LuxuryLeMansLa.

Punch,
Isn't the valve train usually the limiting factor? I was taught that if the iron or steel parts are strong enough, ie forged, the whole problem would be keeping control of the valves. As long as the heads are set up correctly so that the valves are under control, not bouncing off the seats or floating, all is well. Is this correct?

Karl

Yes, that is a big deal along with the choke that Tom spoke about. The engine design and the lightness of parts is also a big deal. It`s nothing to spin a sbc to 7000 grand with not much fancy in it. It`s guts are much lighter than a poncho.

The Poncho`s biggest problems with revving is the choke factor, valvetrain flex/bounce and the weight of parts. But, they don`t need to rev like a sbc to make power.

[72LuxuryLeMansLa.]

Originally Posted by PunchT37

Yes, that is a big deal along with the choke that Tom spoke about. The engine design and the lightness of parts is also a big deal. It`s nothing to spin a sbc to 7000 grand with not much fancy in it. It`s guts are much lighter than a poncho.

The Poncho`s biggest problems with revving is the choke factor, valvetrain flex/bounce and the weight of parts. But, they don`t need to rev like a sbc to make power.

By "limiting factor" I meant things not able to mechanically hold up to the rpm if the engine in fact can spin that fast, ie air in and out. If the engine can't get up the speed because of lack of air and fuel, well that takes care of needing a rev limiter doesn't it.

Thanks Tom and Punch,

Karl

[72LuxuryLeMansLa.]

Originally Posted by old66tiger

Forged crank, rods and light pistons, I have my rev limiter set to 6500, shifing at 6300 or so. With the hyd roller and solid lifters, it pulls like a freight train on acid all of the way to shift point. In most instances, it revs so quick, it is hard to keep if off the rev limiter.

That is a great "problem" to have isn't it?

Karl

[old66tiger]

The throttle response with the EFI is simply amazing. Floor the gas and the engine goes right to target and makes a butt load of power right now.

[Old Man Taylor]

With stock rods I limited it to 5600 RPM. With the '62 forged rods ("rubber rods") I took it to 6000 RPM. With my race 400 I shifted at 6800 and went through the lights at 7200. That has Crower rods, Ross pistons and a stock crank.

[lust4speed]

So many variables to consider that it is pretty much impossible to know what RPM the power is going to stop - and seat-of-the-pants is going to lie to you every time. Big cam with mild heads is going to give up way sooner than a moderate cam and well ported heads. My engine in the Cruiser is a very mellow HR cammed 87 octane 400 with some well ported 670 heads. Doug's headers and ported stock cast iron intake manifold round out the system. The engine was put together before the off-shore aftermarket rods were introduced, so it has prepped stock rods with ARP bolts. Two different chassis dyno's several years apart said maximum horsepower was at 5,900 RPM with a fairly flat torque curve leading up to it. That high of number was surprising considering the compression ratio and cam, but the whole system was designed to let the engine breath. You need to think of the performance potential as a chain with total performance limited by any weak links.

Out on the street through the mufflers the Cruiser runs just about as good letting the 200-4R trans shift by itself at 5,200 RPM - even though the dyno only showed a six horsepower loss through my exhaust. You might be making horsepower at an elevated RPM, but that doesn't mean that you might not be just as quick shifting sooner and letting the converter and the engine torque do their thing.

[Old Man Taylor]

Originally Posted by lust4speed

- - You might be making horsepower at an elevated RPM, but that doesn't mean that you might not be just as quick shifting sooner and letting the converter and the engine torque do their thing.

A converter? On a street car?

[lust4speed]

At first I was "huh?", then I remembered that you are our supreme leader of 4-speeds forever on the street movement.

[firechickenman]

I have my shift light set at 6500 with the 1-2 shift happening at about 6700 and the 2-3 about 6600. That's where it ET's the best. I can feel it nose over just before the light comes on so I'll say it pulls hard to 6400. I have a 7000 chip in the rev limiter. Stock crank, forged H-beam rods, and heavy TRW pistons. Home ported 670's that flow 245 cfm on the intake, Torker II intake and 850 carb. The cam is a Comp custom SFT 250/256 @ .050 with a 110 LSA installed at 106 ICL.