[71malibu406]

from my experience riding even in your own car is far different from driving it, let alone riding in someone else's car that you are not real familiar with. my car doesn't seem that fast to me when i'm driving it, but when i let my buddy drive it it felt completely different. this is just my opinion, but i don't think you will pick up much of anything by just changing header tube size while still having the same collector size and type. you might pick up a little torque, but i think it will be minimal. let us know the results if you do the swap.

 

[mr 4 speed]

you really can't compare a stick car to an auto as far as seat of the pants goes.
Totally different feeling.
I bet if Vince's motor was in Joe's car it would feel like a different motor.
And vice versa
JMHO and experience

 

[69-CHVL]

You guys maybe right regarding the lack of a diff going to 1.75. I just remembered, that when I had the 454HO (low compression, rect. heads, small cam) made huge torque down low, even with the 2" that should of made the "mismatched" combo even worse, but it didn't. I'm begining to think the cam is the issue, as Joe suggested. I think the 454HO cam 211/230 was on a 114, vs. this 110. I guess its doing what it supposed to: create a "peaky" power curve. I have to shift very fast to keep the motor in the sweet spot. I have a tendency to stretch-out each gear too much.

Good cam for racing I guess, but overall street driving the 110 may of not been the best choice. I think I shoulda gone with something on a 112 at least, being how wide a range this motor has to operate (accelerates and cruises at less that ~2000 rpms). Need torue down that low.

 

[69-CHVL]

I guess the question would be, what would give me more torque, a different cam, or headers? Cost we be about the same.

 

[GRN69CHV]

Absolutely correct Chris. My setup feels like one continous/seemless rush of power. One thing I always questioned was the thinking that narrow LSA's work for stick cars, wider for automatics. Maybe back in the day of M22's, but today's trannies are often abnormally wide ratio. Yes for flat out drag racing, but for all around driveability, you want the widest powerband you can get.

 

[383Malibu]

I'm certainly not a cam guru, but most of the cam designers that I have talked to determine the desired valve events and let the lsa fall where it may (kind of like setting the stroke and ring package and letting the rod length fall where it may...). As for narrow LSAs for stick cars and wide LSAs for automatics, ProStock cars with their 120°+ LSAs will put that generalized theory to bed rather quickly.

 

[kjett]

you really can't compare a stick car to an auto as far as seat of the pants goes.
Totally different feeling.
I bet if Vince's motor was in Joe's car it would feel like a different motor.
And vice versa
JMHO and experience

I agree completely. Don't overlook the fact that the converter provides extra multiplication, hence the more linear feel to the acceleration. With a good stall converter your always closer to peak torque than you are with a stick car that has to "accelerate" towards peak torque. My $0.02

 

[69-CHVL]

Bringin' this back to life.

I think I'm gonna try 1.75 headers as a winter project. I kinda have to hack up the exhaust anyway to better fit these mufflers and new tailpipes. I think that my bottom end is a little soft as opposed to where it should be - a 500+HP BB w/3.90's should have stupid torque right off the bottom right? This is kinda lazy till about 2500.

Anybody have 1.75's ceramics that are looking for 2" ceramics? I'd like to keep with hedman so the butchery will be kept to a minimum hopefully.

Ken - where you able to tuck these muffs tight into the body??

 

[Teufelhunden]

Hey Vince,
I am running Sanderson shorties part# BB3. I am pretty sure they make a header for your car and thier prices are reasonable.
If you think you have too much primary, imagine me... my collector is 3" which is reduced down to 2 1/2 then I stuffed a 2 1/4 into that, had it welded and then out to 3" the rest of the way back. I have NO ROOM for anything. Ill have to snap a photo or something.
All this so I could keep my mech linkage for the TREMEC. No x-pipe either... just a really cheap thin crossover.

 

[69-CHVL]

Actually Jeff, these 2" Hedmans fit excellent with the exception of a very minor ding near the steering shaft. And that's probably b/c my driveline angle is down too far. Once I "raise" the motor/trans up a bit - it wont even touch.

 

[kstanbach]

Best 60 is 2.0, with drag radials 275/50/15, its just tough w/a stick to 60 good. If I just drop the clutch it will smoke 'em through the whole 60.

I'll get better though...need to try the MT DR's

getting the clutch issue under control would do a hell of a lot more than switching to smaller headers.

 

[69-CHVL]

It has been my friend...see sig.

 

[kstanbach]

http://www.umtrnorth.com/forums/
read some of the tech on there about slipper clutches.

 

[69-CHVL]

 

[aukai]

Vince if you have traction problems I didn't see it here in this thread you have changed to the MT ET street bias tires haven't you . My only time at the track my 60' was 1.72 now this is old school but my launch rpm ended up at 5K it still hooked but it is because I am using a 15 LB. flywheel if the car dead hooks and bogs the motor I would use a 35 LB. wheel but our cars make enough HP to blow the tires off so that is why I have been using the lighter wheel. instead of playing with low launch RPM something to think about for our tires anyway. For me there are no drivability problems either.

 

[69shovel&90454SS]

Think I'm gonna try the 1.75 headers. This motor lacks bottom-end, and I feel its way too soft considering I just put 3.90's in there. This is exclusively a street car, which cruises at low rpms. I just took GRN69CHV's ride, whose combo is very similar to mine, and his makes stupid power down low. Granted, he has a converter vs. my stick, but I also have a bit more gear to help out. He has 1.75's.

Anybody wanna trade a nice set of 2'x3" ceramic heddmans for the same thing in the 1.75 flavor?

Just a thought...are you sure your ignition timing is coming in soon enough? If you feel a big rush of power at 3000rpm and soggy below like you indicated in one of your posts, I'm thinking it may be a tuning issue. That would be a nice easy fix instead of gutting your exhaust!

 

[69-CHVL]

Mike no traction issues since the ET streets. I got a best '60 of 1.76 once, but 1.8 seems to be the norm. But, I'm just starting to get a feel for the car. The 1.76-1.8 are based on a 2000-2500 fast release. I'm gonna try and do 3000-4000 rpms launches next time out, I'm sure the '60's will come down. I'm pretty sure I can get into the 1.6 range or better once I start leaning on this thing. How did your car handle with 15psi - my ride was pretty dangerous like that.

John, my curve is in by 2000rpms.

Since the TKO has been installed, I rarley drive over 2000 rpms in any gear 95% of the time. Any boost in low-end would be welcomed

 

[crankitup]

Vince, you have a private message.

 

[aukai]

Vince my trans has been out sending parts to be machined I haven't run the ET's yet I was told to start at 16 to 18 LBs though. The passes before where on borrowed 28x9 MT slicks on 8" rims and the car moves around a bit I have 10" rims now hope it helps stabilize the wiggle.

 

[69-CHVL]

Good thought on the 10" wheel.

Another thought regarding header sizing - I was doing a search and its been said that peak tq/hp are moved upward 500-1000rpm for every 1/8" increase in primary size. That's a big deal, and would totally explain the soft bottom end. If my motors pk hp is ~5600rpm +/- and pk tq 4500, and these header move this point to 6600+ rpms, I have a major problem.