1 7/8th for stock internal?

[LS1TOY]

hey im currently running 1 3/4 long tube 4 into 1 headers with a 3 inch collector. i was wondering if changing to a 1 7/8 primary would give any top end gains on a stock internals ls1? setup is fast 90/90 (to be ported) and fitting a meziere and 25% udp. thanks,
Jake,

[squee]

I believe above 3000rpm the gains are around 8hp going from Pacesetters to TSP 1 7/8ths according to TSPs dyno comparison.

[LS1TOY]

Thanks for that, exactly what i was after! seems like a worthwhile gain to me! although 3 hp would have as well!
Jake,

[squee]

Just to let you know, there was a small loss of torque below 3000rpms though...

[Mr. Luos]

I don't think the gains are worth it...unless you are able to sell the ones you have for a decent amount.

If you are geared properly...they will shave off a little of your ET.

[LS1TOY]

Thats cool, im racing stock internals so the car doesnt drop below like 5000rpm!
Jake,

[LS1TOY]

They should only cost me about $600 au which is about $300 us to you guys at the moment!
Jake,

[Mr. Luos]

Thats cool, im racing stock internals so the car doesnt drop below like 5000rpm!
Jake,

Heads/cam? Those stock as well?

Gears? A4/M6?



I don't know exactly what cam/heads TSP used to get 9HP gains. Stock or otherwise.
May be a better way to shave off a couple tenths than getting that little gain on the primaries.

[LS1TOY]

stock heads and cam. m6 with 3.9 for street and 4.11 with a spool for track.
Jake,

[Mr. Luos]

I would say the 1 3/4" headers are perfectly fine.


I didn't even consider the 1 7/8" until I up'd the cubes.

[LS1TOY]

Would i gain any thing above 4000rpm? im chasing times at the track. will be changing engines later in the piece but want to run a 10 sec stock internals first!
Jake,

[Mr. Luos]

A full 1/4 mile?
Supercharger? Nitrous?
10 second with stock heads and cam requires a power adder.


Is the timing/length different down under?

[LS1TOY]

Yeah its the full 1/4 mile. No power adders allowed and no nitrous either! Its not impossible the current record here in australia is 11.07. I read on another forum of a guy with a firebird who ran a 10.6x stock internals, which is amazing. at the moment ive run an 11.4 and still have lots of ways to remove weight and add a bit of power here and there, and at the pointy end 3-5hp is huge. here is a profile on my car
http://www.gmmotorsport.com/gm_ls1toy.shtml
Thanks for you help.
Jake,

[Mr. Luos]

Very cool car!!!


What does it weigh?
You would probably get 6-7RWHP (my guess) above 3500-3700 RPM's with the larger primaries.

[LS1TOY]

Thanks mate! its basically like a gto but with a tub in the back.
out of the factory it weighs about 1600 kg or 3550 pounds. but with some light weight parts i am getting and have got it should be around 3000 pounds or so. its got irs suspension which doesnt help launches but, i have done a 1.6 60ft on the 3.9 and am chasing a 1.5 with the 4.11 and less weight maybe a high 1.4
ive got a broken arm at the moment so i cant drive it but im hangin to get back out there.
Jake,

[Mr. Luos]

Good luck on those ET's.

That is MOVING for a stock internal car.
I like the Ute's.

[squee]

TSP did the test on a completely stock motor with the exception of the fact that it had a Fast intake. Other than that it was bone stock.

[LS1TOY]

Looks like a goer then! thanks for you help guys!
Jake,