Are all big blocks created equal?

623 Views 10 Replies 5 Participants Last post by 25thfox, Jun 1, 2009

stang93mustang

Discussion Starter · May 31, 2009

I got into a debate with a friend of mines yesterday as he called me from the track. The debate was that he claims that if he put a 9000 rpm :happyhapp chip in the car it will help him out in the big end of the track. He ran out at 8000!

Here's some of his specs. Chevy 454 with some good parts (close to 16 to 1 compression). Has a powerglide trans, 4.88 gear, 9 x 29 (?)slicks, he has a low profile manifold w/ a 1150 dom carb. I tell him the manifold has to go, it is a restriction for him. He says no it's fine.

His best results that I know of which was just yesterday was a 10.70 @ 120 something MPH. His 60' was only a 1.5. He's says running 10psi in the slicks before burnout. Nothing major to his suspension besides the 12 bolt, race springs and shocks.

My thing to him is that the motor should not have to work that hard for the results he's getting. I'm saying that he should go down in gear to help compensate for that and he's insisting that no just put a bigger chip in.

He doesn't have a 25-30 grand motor built so the parts are not there to run those RPM's. Good motor but not THAT good!

Any comments on this?:headscratch:

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· #2 · May 31, 2009

i will agree with you on this

Being an old chevy BB guy turning those kind of RPM's is unheard of on a "shade tree" motor

BB Chevy's are torque monsters not rpm motors......

if he puts that chip in the motor he will be seeing his crank sooner than he expected and it will be a lovely view from the hole in the oil pan.....

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stang93mustang

Discussion Starter · #3 · May 31, 2009

Do you think that the low rise manifold is hurting him in the 60'? He has Brodix box stock heads, so good heads plenty of carburetor but in my opinion a restrictive manifold.

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05horse

· #4 · May 31, 2009

the classic 400 BB ( 454 pre stoke. ) are` like RLG said, torqe not rpm

9K is a death sentance on that car

7 K is out of powerband i belive, as far as i know if hes useing an older 400 block, or even a newer one, the powerbands are way low.

will my trans am motor pull 5K yes, will it pull 7 K yes.

do i ever have it past 4K no

thats why my TA has like 2.56 in the rear or something like that.

classic BBs dig low RPM and they produce Monster Tq.

for 9 k rpm id start with a small block or a good tuned LS1 atleast then build it up

im not sure about the manifold, mines still stock.

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stang93mustang

Discussion Starter · #5 · May 31, 2009

05horse said:
the classic 400 BB ( 454 pre stoke. ) are` like RLG said, torqe not rpm

9K is a death sentance on that car

7 K is out of powerband i belive, as far as i know if hes useing an older 400 block, or even a newer one, the powerbands are way low.

will my trans am motor pull 5K yes, will it pull 7 K yes.

do i ever have it past 4K no

thats why my TA has like 2.56 in the rear or something like that.

classic BBs dig low RPM and they produce Monster Tq.

for 9 k rpm id start with a small block or a good tuned LS1 atleast then build it up

im not sure about the manifold, mines still stock.

Yes, I believe that he has way too much gear in the rear. I believe that I could even go down with my 3.89 to a 3.27-3.55 but I just changed from a 4.57!

This is a guy that seems to only listen to one person so after this thread goes dead I'm gonna print it out and give it to him!:hihi::hihi:

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KLWorra

· #6 · May 31, 2009

Heads and Cam? I would think the cam would be the determining factor in the combo then maybe the heads. It would take a monster set of heads to feed a beast like that.

I suggest running some what if scenerios in a computer simulation like engine analyzer before going much further with the combo.

If this guy does have the heads and cam that could breathe and not float up to 9000, then surely 1050 is WAY too small. He would need about TWICE that.

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stang93mustang

Discussion Starter · #7 · May 31, 2009

KLWorra said:
Heads and Cam? I would think the cam would be the determining factor in the combo then maybe the heads. It would take a monster set of heads to feed a beast like that.

I suggest running some what if scenerios in a computer simulation like engine analyzer before going much further with the combo.

If this guy does have the heads and cam that could breathe and not float up to 9000, then surely 1050 is WAY too small. He would need about TWICE that.

I don't know the specs on the cam but I can say that this motor snarls really tough! Close to 16 to 1 compression, I'm sure he has adaquate heads just not a good selection on the manifold. He claims that when the motor had a tunnel ram on it from the previous owner it ran 8's. I asked then why not go back to that set up?:headscratch: I can't believe that a manifold could change things that much. I know there is the equasion of the vehicle weights.

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KLWorra

· #8 · May 31, 2009

stang93mustang said:
I don't know the specs on the cam but I can say that this motor snarls really tough! Close to 16 to 1 compression, I'm sure he has adaquate heads just not a good selection on the manifold. He claims that when the motor had a tunnel ram on it from the previous owner it ran 8's. I asked then why not go back to that set up?:headscratch: I can't believe that a manifold could change things that much. I know there is the equasion of the vehicle weights.

High compression is OK, but based on the trials I did with Engine Analyzer, it didn't pay off as much as a good set of heads, a good cam and a free breathing manifold with a BIG carb.

I think I can believe the tunnel ram helped alot, the wave reflection effect would be significant on a race engine like this.

Of note one quick way to determine if carb is too small or big is to see what the vacuum is at Wide Open Throttle (WOT). If it is bigger than 1.5Hg then too small.

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stang93mustang

Discussion Starter · #9 · Jun 1, 2009

Thanks for all of the comments on this. I know I'm not crazy. I just got back from this guys house and he is dead set on this motor running over 8000rpm with a 9k chip in it.:happyhapp

I hope his pockets are fat because he's go to need to dig deep in them to replace things.:hihi:

We have planned a trip to the track together so we can shut one or the other up. He says he has a couple more tunning tricks and "it's on!" You know I'll advise when this happens.

Looks like I will get to witness his devistation from my mirrors as I cross the finish line!:racer:

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cindys_sn95

· #10 · Jun 1, 2009

just agree with him, go ahead put that 9000 chip in it.. :hihi:

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25thfox

· #11 · Jun 1, 2009

That is going to be the end of that engine. Let s know what happens

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