Pump Gas Limitations

[NOMIEZVR4]

great thread...I was only able to run 14lbs on my setup before knocking on pump 93. Later I found out my car was burning some oil(WTF...only 4k miles on the rebuild!) so it was fouling the plugs out...I'm gonna re-ring the bottom end myself this time around and hopefully this spring i'll be able to contribute some useful data to this thread.

Its crazy you're absolutely right, EVO's with stock turbos and upgraded I/C and cams have no problem running mid-hi 20's boost ...im so jealous.

[IPD]

Just DR heads. Matt M spent YEARS buying NEW sets of heads and applying different combustion chamber designs in an attempt at eliminating the hot spots in the cylinders. I can't for the life of me find that thread but it dates back to the early 2000 era of 3si back when Matt shared a lot of technical info.

BTW my DR750 car will be running a stroker.

i'd like to see some numbers/data to back up that claim on DR heads. i'm not really seeing how you can possibly modify them THAT differently that it will provide substantial benefits that other stage 3 heads do not have.

i almost was going to run 750's on a stroker, but matt himself said it would be a waste, so i'm going with 16g's instead.

[JasonY]

I went 11.1X at 125mph on DR2 heads with old school DR650's on pump 93 and meth at 22-24psi(fell to 22psi) Could run 18-19psi on straight pump. ARC2 only fuel control. Stock heads came setup, 14-15psi reliably. 16 was doable, but zero knock is better than 5-6 for 1psi. That was just the stock valved stage 2's also.

Other than Abram has anyone even come close with that setup? Only weight reduction on my car was 1pc CFDS, Tien coil overs, 18x9.5 TE37's. DSM sidemounts and DNP hardpipes, 500ccs of meth, plus the normal supporting mods of a 3/S circa 03/4.

Jason

[TurboSinceBirth]

I skipped pump altogether because our 91 is even worse than 93. On smaller turbos I couldn't get past 14 psi without knock which was one reason for switching fuels. I'd be curious to see what you guys come up with.

[R/T93]

Debating dropping the coin for one. He needs to make a rear one too!

He does make a rear one.

[J. Fast]

Anyone opposed to running low 20 to mid teen timing at 20psi on pumpgas? I ran my 19t setup like that for years with zero knock issues. I don't understand why you guys are having knock issues at 15 psi on pumpgas. Sounds like its a combination of heatsoak, really bad airflow, , an climate differences. Dont forget wrong temp range plugs and improper gap are huge knock culprits also.

[TurboSinceBirth]

Mine at the time was definitely heatsoak. You can thank the previous owner installing a crappy auto parts replacement radiator for that.

[mb3000]

My .02 goes to the turbochargers themselves. The vast majority of 3/s owners are pushing their turbos past the compressor map, much less keeping their max rpm/P.R. plot inside of the highest efficiency island.

[futurevr4man]

i know in my experience on my first engine build, i had a 3sx forged bottom end, as far as i know the heads were stock, on some cheeeeaaaapppp 19t's. i ran 18 - 19psi with 0 knock, and i figured that was normal. the compression was also 8.5:1.... maybe i just got lucky? the car ran like a scalded dog, but i never got a pass at the track to prove times. ended up lifting the heads, and then went with my big build.

fwiw, im hoping i can see low - mid 20's on this big build, but its a stroker/DR stage 3 heads with big turbos, so it doesnt really apply to this conversation.

whats interesting to note is even people with strokers and nice heads/intercoolers/turbos are still only seeing 19ish psi on pump. take leonel for instance...



as far as i know, thats all tuned out on 93 pump by ray with no meth.


chris, i share your opinions on running pump, which is exactly what i plan to do on my car. im hoping for mid 600's on pump. and i think the issue is in the cams personally, but i have nothing to prove that...

[vr4tune]

When I switched cams I also did cam gears and ported the heads with 2mm oversized valves. After the switch I wasn't able to run as much boost. I went from 18psi on the pure stock heads and cams to 15psi on the new heads and cams.

I still made more power because of the increase of flow [less resistance in the heads] per psi of boost. Power wise I now make at 15psi what I used to make at 21psi

Right now I'm thinking I can pull a few more psi if I properly degree my cams. I have 3sx gears so I'm sure they are off as well as the cams may not be perfect either. Plus the heads were milled a smidgen. Those three thing all compiled together could be throwing my cam timing way off.