Exhaust Drag Race Questions

[offshore]

I agree going with an open exhaust without cats will need a re tune though or two maps extra expense.

[VKPWR]

i took air filter out on the last run when I harden the shocks

Height will be a major restriction. Jack it back up, stock fe2 gear will do for now.
And put more air in the front tyres. Wont affect your 60's but too low pressures will hurt your MPH.

Do you run filter in or out?

[Blown 454 AWD]

Well at the least it would sound like it's going faster

Cheers

Steve

[VKPWR]

hahahaha

Some guy had a Honda Civic! and I swear it was that loud, the loudest on the night.. and it ran 15.9 GOLD!!

Im over the exhaust thing. IT is what it is and it goes fine and appears there is nothing I left out.... Now all to do is wear out thsoe MT's

[swingtan]

Dropping the exhaust and racing will have one major result; a very hot floor pan.....

The minor results would be...

• Reduction is low end torque.
• lean fueling up top (assuming no tune alteration)
• little to no O2 correction due to reverberation sucking fresh air past the sensors. so the ECM will droop into OL mode and not apply any STFT or LTFT data.

Even with a turbo car, you should at least run a dump pipe out the side of the car, to get the hot gasses away from fuel / brake lines and your feet. If you plan on retuning at the track, I can't see a reason why you shouldn't try it (with the dump pipes). But I wouldn't expect much unless everything else, including your driving skills, is at 99%.

Simon.

[VKPWR]

Hey Guys,

anyone got results form adding 1.8 ratio rockers to a similar setup as below? I am looking for some little gains to get me possible into the 11's wihtout updating my hi stall. Looking at 1.8 rockers my lift will go above 610.. just on or thereabouts whihc would put my heads right into the zone..and with the extra comp I have i think it should work and be worth a few HP.. Anythoughts or experences?

I was looking at updating the cam but no use I dont want to fly cut pistons.. rockers are an easy install ... but is it gonan get me 2-3 MPH... mmm

Hey Folks,

Anyone here got any facts/experience on benefits from dropping the exhaust system when racing on the ¼ mile?

I am questioning whether I can be bothered dropping mine in a couple of weeks at Calder Park.
Application in question:
VY Calais, LS1, CNC 243 heads, 11:3-4 comp, 224/230 stick, DiFloppo 4 to 1’s, 1 ¾ with 3 ½ inch single exhaust system, built auto, 3500 stall, 3.9 diff. – makes like 290 kw or something at the wheels.

Thanks in advance.
Brad

[white lie]

How much lift is on the cam?
If you've already shaved the heads and it runs high lift with 1.7's, you may not have enough clearance with the 1.8's. If it's a low lift cam, then they can help

[VKPWR]

PTV will should have enough, well I have been advised by workshop it will be fine...... Has 58 cc chamber so yeah 30 thou taken off the 243 heads.

intake 0.581
Exhaust 0.588
Lobe Sep - 114°
Intake Centerline - 112°

[white lie]

So you end up with
.615/.622 lift, will liven it up a fair bit IMO. Should fit in fine

[VKPWR]

Worth doing ya rekon.... ? Hoping to go from 12.20 @ 112.9 to 11 something... dont think it will make that much difference... maybe an underdrive pulley as well.

So you end up with
.615/.622 lift, will liven it up a fair bit IMO. Should fit in fine

[white lie]

Will make more of a difference than under drive pulley, that's for sure.

Have you done anything with the suspension? I'm just thinking a head and cam should be running quicker than 12.2@112. I was running that cam only, but I do have a bigger converter and the C4B heads

[markone2]

well i went to calder, exhaust on, wacked the ET streets.. and now not sure if the time is decent.. Ran best 12.27 @ 112.9 MPH with 1.78 60 foots....

any ideas to lower 60 ft n go 11's?

I thought it may have been good for 1.60 60 ft.. obviusly not, 3 runs and all pretty much the same.

Serious rethink of drive line would be number one priority imho……if you have a genuine 290rwkw you should be trapping mid 11’s with ease…I’ve read the posts….if you want to get there pm me, you’ve a couple of major mishaps already as concerns the cars set up imho

Cheers M.

[LS Kernal]

unless you had 400+rwkw you'd struggle to do 1.6's.

need 90/10's, fe2 rear shocks/springs, bigger convertor 4500+ and 4.11's to get into 1.6's. i've got to 1.51 with that combo and ~290-300 rwkw in a vz on a 235 radial

LMAO are you joking? XR6T 406RWHP, 3500 stall, factory gears and suspension, 255 et streets 1.6's all day every day

[VKPWR]

Serious rethink of drive line would be number one priority imho……if you have a genuine 290rwkw you should be trapping mid 11’s with ease…I’ve read the posts….if you want to get there pm me, you’ve a couple of major mishaps already as concerns the cars set up imho

Cheers M.

I PM d u mate. Thks brad

[VKPWR]

So you end up with
.615/.622 lift, will liven it up a fair bit IMO. Should fit in fine

Did a lot and i mean a lot of googling with US forums and such, and almost 'all' do not recommend 1.8 rocker on such a high lift cam and especially on XER lobes...XER273

I cant find anything positive... Have you done it White_lie?

Does anyone else on here have experience in this? 1.8 rockers on .588 lift odd cam.. please...

many thanks.
Brad