[Matt1970gto]

Not the best but a couple pics of my intake. Which appears to be part of the problem

[johnta1]

Have you ever made a full pass with no stop on?

[Matt1970gto]

Originally Posted by Matt1970gto

New to the group & first post. I’m running a DCI 5 combo, the guy that build my Taj Mahal intake also spec’d my headers. The trq numbers were a good bit lower than my previous build & thinking it’s a combination of huge plenum & too big of header tubes 2 1/4 to 2 3/8 5” collector. Anyone else running tubes this big on 1050-1100 hp range. My dad’s combo has 2 1/8 to 2 1/4 w/4” collector, smaller intake plenum as well & made roughly 80 ft lbs more trq.

Originally Posted by Matt1970gto

Not the best but a couple pics of my intake. Which appears to be part of the problem

Originally Posted by johnta1

Have you ever made a full pass with no stop on?

Not completely, last year I had a brain fart while adjusting the close rate on my throttle stop. I left those numbers in so it only stayed closed for .5 tenths of a second @ 3800 rpm. It went 8.69 @ 159 lifting after the 1000 ft. Air was roughly 4400 ft.

[johnta1]

Not bad!

That intake looks like it would be good with a 8-71 blower?



I'm not up on throttle stop workings. When the stop comes on, does the rpm's drop to idle or stay around 3500/4500 rpms?
Also when does yours come on like .2 from launch or later?
From ET slip must be before 60' for sure. Comes back on around .3/.5 into the 'stop'?

My thinking is maybe the rpm's are too low when coming off stop and the car takes too long to get back in power range? (like around 7000RPM?)

[Matt1970gto]

Originally Posted by johnta1

Not bad!

That intake looks like it would be good with a 8-71 blower?



I'm not up on throttle stop workings. When the stop comes on, does the rpm's drop to idle or stay around 3500/4500 rpms?
Also when does yours come on like .2 from launch or later?
From ET slip must be before 60' for sure. Comes back on around .3/.5 into the 'stop'?

My thinking is maybe the rpm's are too low when coming off stop and the car takes too long to get back in power range? (like around 7000RPM?)

Mine & dad’s cars are setup almost identical. The stops come on @ .005 & we’re both on around 3.000. I think I had 3.020 in timer 2 & he had 3.110 for first round at bowling green last weekend. For now both of our stop RPM’s is 4,000. Both 3 speed lenco/bruno. I have a 2.24 low gear & he has a 2.08. He has a 4.56 rear & I have 4.29 now. I lost just over 2 mph when I broke my 4.56 & put my 4.29s in. Lightened gear set ceramic bearings.

[Matt1970gto]

This was last weekend me & dad running each other. I had changed carbs & throttle stops prior to the event & my 60ft picked up a tenth. When me & dad ran each other at Charlotte in the spring we were only a hundredth or two apart until I broke

[Matt1970gto]

Originally Posted by johnta1

Not bad!

That intake looks like it would be good with a 8-71 blower?



I'm not up on throttle stop workings. When the stop comes on, does the rpm's drop to idle or stay around 3500/4500 rpms?
Also when does yours come on like .2 from launch or later?
From ET slip must be before 60' for sure. Comes back on around .3/.5 into the 'stop'?

My thinking is maybe the rpm's are too low when coming off stop and the car takes too long to get back in power range? (like around 7000RPM?)

This is me & dad @ Charlotte this year.

[johnta1]

With that slip, I wonder if your carb is too small? You seem to do good until the last half of the quarter? You're running gasoline also right? Not alcohol?

[Matt1970gto]

Originally Posted by johnta1

Not bad!

That intake looks like it would be good with a 8-71 blower?



I'm not up on throttle stop workings. When the stop comes on, does the rpm's drop to idle or stay around 3500/4500 rpms?
Also when does yours come on like .2 from launch or later?
From ET slip must be before 60' for sure. Comes back on around .3/.5 into the 'stop'?

My thinking is maybe the rpm's are too low when coming off stop and the car takes too long to get back in power range? (like around 7000RPM?)

Originally Posted by johnta1

With that slip, I wonder if your carb is too small? You seem to do good until the last half of the quarter? You're running gasoline also right? Not alcohol?

Yes for gas, when we had my engine on the dyno Trevor Wiggins ( get’m carbs) spent the day with me. We tried a 1450 braswell that belongs to the engine builder first & his fuel renegade 120. Then switched to my carb & fuel ( fuel factory f14). My carb is a get’m 1250 that’s a twin to dads. Trevor also brought a 1350. Both get’m carbs made more hp than the braswell with the 1350 making 6hp more than my 1250. Trevor was at that track last weekend & watched us run, we spoke about putting a bigger carb on my car.. Either a 1350 four hole or a 1400 cfm twin blade

[johnta1]

Are you in high gear when the throttle comes back on?

[Matt1970gto]

Originally Posted by johnta1

Are you in high gear when the throttle comes back on?

No sir, I’m in first the entire time. I shift second then third once I come off the stop.

[johnta1]

This could be a whole new thread.



I would think that for consistency and stuff that you would be at least in 2nd gear?
The chassis unloading then loading, time of shifts, etc. would be not very consistent. The engine having to rev then idle then rev also.

[Matt1970gto]

Originally Posted by johnta1

This could be a whole new thread.



I would think that for consistency and stuff that you would be at least in 2nd gear?
The chassis unloading then loading, time of shifts, etc. would be not very consistent. The engine having to rev then idle then rev also.

It’s possible, most people that have power glides shift while on the stop. I think if I tried to manually shift even once while on the stop I would be less consistent. Especially since I’ve been doing it this way over 20 years. In 2016 I finished 4th in div2 Ihra & 6th in div2 nhra points & didn’t have a shift light. Thinking back on it maybe I should disconnect or cover up my shift light now lol.

[Stan Weiss]

Matt,
What might help is if you have data logging you could post.

Not sure what run I saved the data to simulate, but this is what I get for acceleration /G's

Stan

[Matt1970gto]

Originally Posted by Stan Weiss

Matt,
What might help is if you have data logging you could post.

Not sure what run I saved the data to simulate, but this is what I get for acceleration /G's

Stan

Unfortunately at this time I do not have any data log info. I have a racepak sportsman just waiting to get it wired up.

[Matt1970gto]

Originally Posted by Stan Weiss

Matt,
What might help is if you have data logging you could post.

Not sure what run I saved the data to simulate, but this is what I get for acceleration /G's

Stan

Don made a couple suggestions the other day when we spoke.. Welding the head up to reduce the cross section, going to a 2.400 valve but would still have a csa around 93% & having a different cam cut by Scott Brown. I got a quote a couple months ago of close to 10k to build a new intake.. 10k for intake, 2500 headers, rework the heads , new cam & at or above a set of tigers or pro ports. Just not sure how much more I want to go down the rabbit hole.

[Stan Weiss]

Originally Posted by Matt1970gto

Don made a couple suggestions the other day when we spoke.. Welding the head up to reduce the cross section, going to a 2.400 valve but would still have a csa around 93% & having a different cam cut by Scott Brown. I got a quote a couple months ago of close to 10k to build a new intake.. 10k for intake, 2500 headers, rework the heads , new cam & at or above a set of tigers or pro ports. Just not sure how much more I want to go down the rabbit hole.

Matt,
If I remember correctly you and your father started out with the same head casting, but had different people do the work and, his engine had a much better torque curve.

Stan

[Matt1970gto]

Originally Posted by Stan Weiss

Matt,
What might help is if you have data logging you could post.

Not sure what run I saved the data to simulate, but this is what I get for acceleration /G's

Stan

Originally Posted by Stan Weiss

Matt,
If I remember correctly you and your father started out with the same head casting, but had different people do the work and, his engine had a much better torque curve.

Stan

Stan, that is correct. Both castings were originally worked by Jim Roberson. Our engine builder wasn’t happy with them . We sent dads to someone (not sure who) that owed our builder a favor & my heads went to the guy that built my intake. With what I’m seeing on the track & what those that have looked at my heads the guy opened my up too much., Add that to a huge intake & I’m struggling. The guy never gave me the measurements but we had mine intake & dads ran through CAD. I know my runners are slightly shorter @ 5” vs 5.37 & dad’s cross section is 90% vs my 94%. I hate the idea of starting over again but I also hate the idea of throwing more $$$ into this build. We have a new profiler casting DCI 5 head but haven’t had any luck getting anyone to work it,

[Stan Weiss]

Matt,
Have you talked to Ed Page screen name RAIV-Z here on PY. He has a twin turbo 535 ci with DCI RA V heads. I believe this past year he had John Marcella do some work on them.

Stan

[Matt1970gto]

Originally Posted by Stan Weiss

Matt,
Have you talked to Ed Page screen name RAIV-Z here on PY. He has a twin turbo 535 ci with DCI RA V heads. I believe this past year he had John Marcella do some work on them.

Stan

I haven’t but I will. Frank @ all Pontiac said if anyone could make them work it would be Marcella. Thank you.