What size headers
 

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.

On the headers it is a combination of tube diameter and tube length.

You say your Fathers combination has less plenum volume than yours, what about total intake track length for each combination?

Stan

We’ve had both intakes scanned I’ll have to find that information. Wilson intake built my dads & made two hats for it, a single & a dual. Self Racing built mine. I’ve had a local guy take some plenum area out of my intake last year & it helped some but still not right. Yet to make a clean pass with it, it coughs, spits , sputters & tries to die on the launch. The general consensus is the intake is so big it’s losing carb signal on the launch.

What size carb do you run?
Have you ran the dual 4bbl top?


:confused:

I run a 1250 Get’m carb that is a twin to dads. My intake is strictly for one carb. I have a 1050 on now that I will try next week. Was hoping to run this weekend but our little girl has been pretty sick the past week & we’re all struggling right now lol.

That is definitely a large header. Not sure if you're trying to get the 80tq that your dad is up or what you're looking to gain. But my honest opinion is it'll take a combination of intake and header work. If the plenum is so large you're having issues on the leave that's definitely not right and you will see gains once that is fixed (I'd bet your shift recovery is bad also due to it).
One thing you could do with the headers is move to a 4 or 4.5 inch collect and lengthen it. See how that works. I'm guessing yours are removable so that would be a very easy thing to test.
Fwiw, I ran 2 1/8 to 2 1/4 4" collector on my 1050hp 511ci.

I just want all I can get & not pull the motor out every 4 or so passes. Apples to apples dads dyno #s were with his two 1050s so I was happy to get as close as I did. His motor made peak trq @ 5800 & mine @ 6700. Peak hp for him was around 7600 & for me over 8000 each piull. As far as shift points once it clears up it’s pulls strong through both shifts. 2.24 lenco 4.56 rear it leaves hard.

Interesting, how different are the cams? By the numbers you posted it would seem your cam is quite a bit bigger?

Launch RPM?


:confused:

Dads is 280/294 .855 .837 115 lobe sep
Mine 284/306 .954 .936 121 lobe sep

Sorry it didn’t post the 1st time for some reason but 5800.

My heads were also hogged out. Once dad’s new set of 5s & his new intake are ready I’ll decide whether I take his old heads or back up & punt. These 5s made good #s on the dyno but we haven’t seen the gains on the track to match the #s. I gained 100hp & lost 60ft lbs of trq compared to my 535 with 11 degree eldebrocks. Dad gained 140hp & about 80 fr lbs trq over his 535 11degree combo. We throttle stop race & the cars are running the same mph with this combo than the old. Both 535s had cams in .763 .780 range & both cars went 5.20s on a single carb i@ Huntsville Dragway.

Just curious who picked/made you cam?
I would try another cam.

Engine builder & LSM.. I had a twin to dads cam in it at first but it was worse.

There is going to be a huge difference between those two cams. That second one is going to move the power band much higher in the RPM range.

A overly large primary tube on a given race motor can sometimes be partially compensated for by a longer then needed collector extension.

Yea, dad’s motor only dropped 11hp from 7000-7800 but by 7800 it was dropping. My motor just starts making good #s @
around 7800 & I pulled it to 8400. Only 7 passes on this setup & no clean runs yet but I was only crossing @ 7550-7600 @ Gainesville for the gator nationals this year.

Talked yesterday to guy that’s helped some with my intake & is working the 3rd set of DCI 5s. He mentioned as someone here did as well swapping the collector. He said go with a longer 4” collector. I can’t go much longer & still make it fit but it’s an option. Mine & my dad’s cars were supposed to be identical builds but my his headers hit my steering so I can’t try his.

Can you post dyno sheets for both engines?

What does each engine have for stall speed?

Stan

Both have 6400.

Is your throttle stop/delay one that has you at an idle/set rpm then opens when ready to go, or on the mat and the 2 step keeps it at a set rpm until ready to go?


Nice dyno sheets!


:)

My stop rpm is 3750 & remain in low gear while on the stop.

What does your fathers car weight and what et does he dial?

Just a WAG using 3350# race weight.

1000 Foot ET = 8.4412
1/4 Mile ET = 9.9051
1/4 Mile MPH = 155.9576

Stan

His car weighs 2750, mine is 2800 & change , I plan to weigh it next week @ the 4 wide . I am guessing I’ll be around 2825. We both run super gas 9.90. He’s usually 9.90 @ 158-160, with his single carb his best mph is 162.At the gators he was having issues & his mph had dropped to 155-156. I was running 157 there. & never making a clean pass. We have matching 1250 get’m carbs on both. Both cars have 3 speed lenco/bruno combinations. 2.08 1st for him, 2.24 for me & both have lightened 4.57 gears. Mine was built to be a twin to his but that never works out. Both have Bickel chassis as well.

My simulations below 1000 foot with a throttle stop are way out. About 10 years ago here on PY I did do some simulations for someone who was running a .90 class. The idea for to see what MPH increase they would get from more HP but still running the same et. The simulations were fairly close.

Thank you for that information.

1000 Foot ET = 8.4739
1/4 Mile ET = 9.9008
1/4 Mile MPH = 160.2311

How close is my 1000 foot et?

Stan

Pretty close actually. Here’s a time slip from bowling green last year. I’m 2464 & killed 4 mph.

Dad is 2537 that was this morning at Reynolds Ga

Good luck down in Reynolds! You guys have them Pontiacs flying! Say hi to Dave P and Kevin M for me.

Dad & my sister made the trip. Our daughter had RSV & parainfluenza last week. It’s been a rough week or so here.

Thanks. What is the weather? I pulled some HP and shorted the time of the stop.

1000 Foot ET = 8.4353
1/4 Mile ET = 9.8825
1/4 Mile MPH = 157.8409

Stan

Can you adjust the the time when the throttle 1st close? (like 1 second into launch)
Delay closed is around 2 seconds?

Also actual carb being throttled or a butterfly in spacer under carb?

Hope your daughter is better.

Sorry your Daughter is not feeling well :(

I lined up with Laurel on a Time run today.

Sounds like the headers are too big. Try adding the extension to see what happens. Maybe after Charlotte, ask dad if you can try his intake. lol

I wish I could try his intake & headers..

Your mph is down , your wedge motor not wedging?

Yes, I have timer one set to come on @ 0.005, this is a carb with under the carb stop but I also have a APD maxspeed with the stop made in the carb.

I don’t always claim Laurel & most dont know me on here yet so don’t give them clues lol.

Hope your daughter is feeling better.

Maybe someone else will look at this and see it as one thing. I don't know what it is, but think it has to be a combination of parts.

Stan

I agree Stan, I think it's a combination of parts that's causing his issue, not 1 part.

Both times I’ve had it on the dyno the guy said your problem is that 55 gallon intake you have. It barely made 1000 hp the first time. We changed cam & took some plenum area out & made 1071.9. I’ll message the guy again for the intake scan information. Not the best pics but here is a before and after of the inside of my plenum.

Here is the pic not cropped of how it was when I got it. We thought the plenum area was huge right off the bat. Sent pics to Don & he disagreed thinking it may not be big enough.

Am I correct in that the 2 engines were dynoed at different places?

Stan

Our engine builder dynoed both & then we carried them to another place to try & do some tuning. Dad’s dyno sheet I posted was from the engine builder & mine from the other. have the ones in the shop if I can find them of where it was dynoed at the place where I posted mine. Best I remember peak hp to peak hp was 2 hp difference between the two. 1109 vs 1111.

Here is one dads pulls from the same place. Dad’s pulls were made @ 300 vs mine @ 600. 11hp difference in our avg hp #s.

Thanks for the new dyno sheet.

True but his is over a 2000 RPM range and yours is over a 1400 RPM range.

Stan

When you look at dyno sheets, you need to look at all of the numbers.

These are your Father's HP curves from the 2 dyno sheets.

Stan

Had to put the Hi Port motor back in after breaking a valve spring in Orlando. Wedge motor is back on the stand, almost finished, try again soon..

What made you go with the wedge over a set of tigers? Hell I’ve been asking myself why we went the RA5 route .

I think your Father's engine turned out quite well. I would be interested in how much better you think it would have been with Tiger heads? For me the elephant in the room is. If your engine was to a sister engine to his why did it turnout so much different?

Stan

How have the Super Wedge heads turned out on big time engines ?
There does not seem to be a lot of info on them.

Different person rework my heads & built my intake. Based on the flow #s he got he recommended the bigger cam & header tube specs.
Not sure it would’ve turned out better but it sho would’ve been cheaper. I have saw tiger builds make good power & some not make good. Our 5 builds looked good on dyno but on the track I’ve yet to see a performance upgrade. We’re at Charlotte for the 4 wide so I will have a better idea tomorrow but I ran 9.90 @ 158 here in 17 with my 535 edelbrock combo that had a 1200 quick fuel. I just put a 1175 carb on my motor so we’ll see how it does. Dad ran 8.90 @ 165 with his 535 edelbrock combo & has been 8.90 @ 165 with his 5 combo. We added 30-35 cubic inch , head flow cfm went from 420s to over 500 & both got bigger cams.