How much are my small headers killing my performance

I have a 900 horsepower W7 small block with 1 7/8 headers on it. I put more gear in the rear end. (4.88 to 5.38) and more converter doesn't seem to make much difference on the performance. I'm thinking the headers are holding this thing back big time..runs 9.20s in 3000 da air @ 2800 lbs ???????????

We have tried about everything possible with headers and never found over a few hundredths going from what we thought was a great set of headers to what we thought was the worst set of headers. I hope you have better luck chasing et with we exhaust than we did.

[quote=hustlin hoosier]We have tried about everything possible with headers and never found over a few hundredths going from what we thought was a great set of headers to what we thought was the worst set of headers. I hope you have better luck chasing et with we exhaust than we did. [/quote
I got some headers with the motor but will take a ton of work to get them to fit..but I may try this winter.. they are step headers..2inch 2 1/8 to 2 1/4....I'm shifting this thing at 8700 rpm and thought at that rpm small header is choking it

What's the MPH?

It's making HP then. Gears typically don't make a big difference. You might look at the stall on the trans brake, and decide if it's getting into the torque power band. Case in point, my dragster picked up from 7.80's to 7.50's and .60's because the one I was using stalled below the torque power band. It would make a lot more difference in a 3000 pound car.

By the way, header size, as already pointed out, won't hold you back much unless they are really wrong for the application. JMO

that's just it. I think they are considering the step headers that were on it when the previous owner was running it.. Converter is 7000 stall and motor makes peak hp at 9000

And peak Torque? I'm going to guess it's over 7000? I'm not a small block guy, so I could be wrong.

Peak torque 586@7200

Well, if you have actually checked the stall, and I assume you have, I would look at tune up and such. Again, I'm not a small block guy so someone here might have another idea. My max torque is at 6400. If the stall is under 6000 RPM, I'm 2 tenths slow.

7000 stall

Tried shortening the collector?

It's "900hp", what headers were on it when it made 900hp?

2800 lbs, 148mph shows 700hp on the moroso chart.
Figuring 10% loss for air quality, parasitic losses, etc, you're still off over 100hp.
I don't know if the headers would be worth that kind of power.

Step headers...2inch 2 1/8-2 1/4. I have the other headers just need to do a lot of modifications to make them fit

At seasons end...... Might be worth a trip to the dyno and see just how much difference in power there is between the headers......before going through the effort of fitting them to the car.

I need to talk to someone about it that knows more than me that's why I'm asking.

Isn't Dwayne Porter a small block guy?

Mmmmmmmm, not particularly.

Never even laid my eyes on a W7 head in person.

Unless someone has tested a motor combo that's very close to yours with both sizes of headers you're talking about, and they're willing to share that info, you might have to test if for yourself to find out exactly what the answer is....... On your motor.

100+ hp seems like a stretch for a header swap to me....... But that's what the dyno is for.
To provide answers to those questions.

If max hp is at 9000rpm why are you shifting at 8700?

I don't know a thing about W7 engines but 900hp sounds a little optomistic.

[quote=GomangoCuda]If max hp is at 9000rpm why are you shifting at 8700?

I don't know a thing about W7 engines but 900hp s
ounds a little optomistic. [/qu
I got the dyno sheet. I bought it from a well-known super stock racer. Just trying to get it to run like it should

In that case you should be able to ask the guy you bought the engine from what headers you should use. Anyone who runs superstock probably has a garage full of headers that they have tried. Might even be able to buy his set from last year and save yourself some money.

I have the headers that came off of it. They just won't fit my chassis without major modifications. Just wondering if all the work will be worth it they are much larger headers.. I'm running. 1 7/8 now and the other headers are step headers 2 inch 2 1/8. 2 1/4.. with this much horsepower and RPM is it really choking it down that much that's what I'm wondering

My guess is the super stock guy probably wasn't using those headers unless they made more power than anything else he has tried.
I would try and make them work and report back.

Those headers may be and probably are hurting you some. Whats the rest of the specs on the headers, pipe length and collector diameter and length.

As Poly suggested , you don't need much of a collector length with a stall of 7000 and a peak hp of 9000 rpm. I too want to know why you shift much lower then hp peak. I'm guessing you tried shifting at and above with no difference in ET???

Pipe size has a rule of thumb with exhaust port flow for port velocity for exhaust scavenging. I don't know what a w7 exhaust port flows. But in general, you size it from that. So whats your exhaust W7 ports flow?

I think that's going to be the plan for now

[quote=AndyF]In that case you should be able to ask the guy you bought the engine from what headers you should use. Anyone who runs superstock probably has a garage full of headers that they have tried. Might even be able to buy his set from it



The headers he gave me we're on this motor on his other car. Nothing will bolt directly onto my car it has a tube chassis

[quote=hustlin hoosier]We have tried about everything possible with headers and never found over a few hundredths going from what we thought was a great set of headers to what we thought was the worst set of headers. I hope you have better luck chasing et with we exhaust than we did. [/q


How much in diameter did you change the header size

Several years back Brian( IMM engines) who posts on here ran two different sets of headers on I believe a stroker W2 motor.
Headmans and TTI headers as memory serves me.
There was a 30 or 40 horse difference between them

I wonder if there was a difference in diameter or length or what?

From everything I've read and heard about this engine combo I would lean towards the converter not being the right stall. That seems to be the biggest issues

To be running w7 heads in a super stock car, it would have to be one of the modified classes.
The whole car was likely set up around that engine package, and I'm sure part of what the op is seeing is that a class car is often a better, more sophisticated overall "package" than a typical bracket car.

Take a stock eliminator motor out of a good running stocker package and stick it in a similar bracket car and I doubt the ET's would even be close.

Another question I would have is, how close to 900hp was the performance of the car the motor came out of? Did the ET/mph/weight show it to be 900hp?

Another thought; an SS racer will kill for .02 ET. If he was running the headers that came were in the car he raced, They are probably as good as it gets, but might not show a lot of improvement. The best answer is try it and see. Be ready to tune for them, and find out EXACTLY what stall you have. I was fooled for years because I went by a tach. I am no small block guy, but hear they are sensitive to converters.

Yes one thing at a time I will put these headers on and see what happens. I had my converter stall raised from 6500 to 7000 that was all they could get out of my 8 inch converter. 60 footed a couple hundreds better but the ET remain the same

Yes his car was probably a whole lot better than mine being a super stock car. But what I really want to know is are my headers killing my motor a tremendous amount I'm going to find out over the winter

What did the car the motor came out of weigh, and what was the speed?

IMO not a converter builder, but it seems to me that in order for an 8" converter to be loosened up enough to stall 7000rpm behind a motor with less than 600ft/lbs, it would lose some effeciency in the process.

I'll throw this out there, not sure if it means much. Read about a test some engine builder did on a small block Chevy, on the dyno, with the results of dinging headers, if it lost power. They went so far as to almost flatten them completely and saw no power loss, maybe 4 or 5 hp tops, they where dumbfounded? You might see a change in a poorly designed set over a top of the line set, but not the gains you're looking for, IMO

That could be true. But what was the horsepower level of that motor? I would think this 900 horsepower motor turning 8,700 rpm it would make a bit of difference.

I would be skeptical of it being 900 hp unless I was there when they dynoed it. Did he say what mph the other car was going? The header banging was a u-tube video. I dought they could fake it.

It Was the Engine Masters show Episode 4 Episode 12 is the followup.

153 mph @ 3280lbs this motor is legit it has the best of everything on it

Are you runing the same converter, trans gearing, and rear gear he did?

no,no,no all I'm wondering is if these 1 7/8 headers I'm using are killing my performance and if it would be worth the work to make the larger step headers work !!!

It would, at least be worth the effort to try them. That much power, with the rpm needed, might be cause for concern with a 1 7/8" tube. The longer the tube, the more the restriction. Works just like resistance in wiring. Smaller tubes, in general, give more torque. Bigger tubes are for mid to high rpm use. You have to watch your fuel curve through mid range with big tubes.

The moroso chart shows that to be pretty much right on 900hp.

Yes I think it will be worth the effort. I've never built headers before but to make these fit shouldn't be that bad I have a tube chassis car there's lots of room. And my time is free

Yes the power is there. Just seems like something's holding this motor back. I've tried a lot of things and nothing really seems to make much difference so this is my next step

It will be interesting to see if your headers are killing 150 horse.

All that header beat up test did was prove that the wrong headers were on the motor to start with....

You need to watch the follow up video. TL/DR answer, no they were the best size.

x2

Not only would you find out what the other headers are worth, it could provide more data to help with converter setup.

I did a header test on my 470 engine between 2" dyno headers and 1 3/4 stepped to 1 7/8 dyno headers. At 6800 rpm the 2" headers were 10 ft-lbs better.

Damn, I'm not so upset with having 1.75 TTI's on my 420 G3 anymore.

Well I finally put in a 7 inch converter and it picked up all most 2 tenths..9.07 @ 149 in 4000 da air..that was the ticket and I haven't tried leaving at higher rpm yet or a little more jet

From experience Make sure your tach is accurate. I have seen people going crazy trying to get their car running like it should only to find the tach was 500-600 Rpm slow. For the hell of it try shifting at 8000 or shift when engine sounds right. I was riding in my buddy Demon that was actually slowing down due to over reving cost him bearings I shifted car earlier and surprise the car et went down Have fun!

My advice would to be to contact Brett Miller or Ryan Johnson and pick their brains. Both have a lot of high end small block experience. Brett is a walking encyclopedia on small blocks, it blows my little mind everytime I talk with him.

Your not gonna see a 100hp difference from the
set you have on the car to the ones that were
on it.. I was running a W-9 with step headers
(1 7/8-2-2 1/8.. if your conv stalls at 7000 it
is real close I stalled at 5600 and it was a bit
low.. I shifted at 8200 rpm.. it didnt make any
more power when shifted at higher rpms.. I went
up to 9400 and dint do a damn thing

What carb(s) are you running............

FWIW the smallblock in the heads up car made over 1000 with a set of 1 7/8" 20 long primary headers on the dyno. Headers on the car are 1 7/8 to 2 to 2 /18". Car ran 8.0's last year at 2800.

Very nice!!!!!!!

had some headers built...1 7/8-2 1/8-2 1/4..didnt see much performance diff..converter made all the diff

one 1200 cfm

I agree on the horsepower being in the 700 range with current setup,given a decent chassis. First off, you say peak power is 9,000 and you shift at 8700? Peak torque is 7200 and stall is 7,000?
My deal makes peak power at 6900, and shift at 7450 and 2/3 at 7300, stall is 6200, but peak torque is 5,000! I dynoed the motor and it said 847 hp, car weighs 3065, i use 2078 Goodyear slicks that weigh 41 lbs each, and the car went 8.900 at 2100 da.
The point of all this info is if ypur tq and hp peaks are what you say, the stall and shift points may be a big part of the problem. Too low. Its dyno time! Get the real dope on the motor and go from there.