Ca'nt get it down pat(tuning)

Bloated Seal · 05-01-2007

93
The problem- I'm getting audible detonation at 12psi in 4th. Below that, it's ok, but I am trying to get 14psi or at the very least, a safe 12 out of it. I am seeking quality tuning suggestions.
The car- '74 vw beetle with a mild 1915 and a small to4. This is a draw through setup with the carb(demon 575, vac sec) placed before the compressor.
alcohol setup- Progressive w/ 2 bar map. m3 nozzle with pre-compressor injection. 100% methanol.
What I've done- Well, prior to the meth, I was at 8psi with a high 10afr @ wot. No hassle. Now, i hear no detonation until 11-12 psi. So far, with the meth, I have tried both a 6-14 ramp and a 8-12 ramp. I have also tried jetting up on the secondary side to richen things up even more(remember, on 8, it was rather rich). I also went a step colder on the plugs(ngk 7's) The best results on 12 psi have come with the original jetting and the 8-12 ramp. With this, only a little detonation can be heard in 4th only, but, of course, any detonation is quite undesireable. On these runs, looking at the lm-1, the afr was jumping around the high 11's- low 12's with the occasional lean spike(I'm quite sure this is due to the draw through design and unavoidable in the present configuration). Last time I checked the plugs(6-14 and richer jetting, I think), they were gray.
The system is definatly working. I am getting the green light. The tank is going down(slowly) and it's definatly cooling the charge. This is surprising as with the draw through setup, all the petrol flows through the comp and intake, yet they would still get quite hot. Now, even at 12 psi, both the compressor and intake stay near ambient with the miniscule amount of meth going through them. It's doing it's job on that front.
To me, everything seems to be as it should. Please tell me how I can run some boost safely, 12 is a world away from 8 and I'd really like 14 on pump.
So- Less fuel, more meth(m5)? A different ramp? A mix(cringe) instead of straight meth? Thanks for any help.
93 93/93

pacemkr86 · 05-02-2007

shoot for a 11.5 a/f with OUT alcohol..
then 10.0 or 10.5 with alcohol

pacemkr86 · 05-02-2007

ps.. post some pics of your setup.. id love to see it

05-01-2007	#1 (permalink)
Bloated Seal Water Injection Newb Year: 1974 Make: VW Model: Beetle Join Date: Nov 2006 Posts: 9	Ca'nt get it down pat(tuning) 93 The problem- I'm getting audible detonation at 12psi in 4th. Below that, it's ok, but I am trying to get 14psi or at the very least, a safe 12 out of it. I am seeking quality tuning suggestions. The car- '74 vw beetle with a mild 1915 and a small to4. This is a draw through setup with the carb(demon 575, vac sec) placed before the compressor. alcohol setup- Progressive w/ 2 bar map. m3 nozzle with pre-compressor injection. 100% methanol. What I've done- Well, prior to the meth, I was at 8psi with a high 10afr @ wot. No hassle. Now, i hear no detonation until 11-12 psi. So far, with the meth, I have tried both a 6-14 ramp and a 8-12 ramp. I have also tried jetting up on the secondary side to richen things up even more(remember, on 8, it was rather rich). I also went a step colder on the plugs(ngk 7's) The best results on 12 psi have come with the original jetting and the 8-12 ramp. With this, only a little detonation can be heard in 4th only, but, of course, any detonation is quite undesireable. On these runs, looking at the lm-1, the afr was jumping around the high 11's- low 12's with the occasional lean spike(I'm quite sure this is due to the draw through design and unavoidable in the present configuration). Last time I checked the plugs(6-14 and richer jetting, I think), they were gray. The system is definatly working. I am getting the green light. The tank is going down(slowly) and it's definatly cooling the charge. This is surprising as with the draw through setup, all the petrol flows through the comp and intake, yet they would still get quite hot. Now, even at 12 psi, both the compressor and intake stay near ambient with the miniscule amount of meth going through them. It's doing it's job on that front. To me, everything seems to be as it should. Please tell me how I can run some boost safely, 12 is a world away from 8 and I'd really like 14 on pump. So- Less fuel, more meth(m5)? A different ramp? A mix(cringe) instead of straight meth? Thanks for any help. 93 93/93

05-02-2007	#2 (permalink)
pacemkr86 DevilsOwn Tech Year: 86 Make: Buick Model: T Type Join Date: Oct 2005 Posts: 644	Re: Ca'nt get it down pat(tuning) shoot for a 11.5 a/f with OUT alcohol.. then 10.0 or 10.5 with alcohol __________________ Phil Underwood My Turbo Buick Last edited by pacemkr86; 05-02-2007 at 10:07 PM.

05-02-2007	#3 (permalink)
pacemkr86 DevilsOwn Tech Year: 86 Make: Buick Model: T Type Join Date: Oct 2005 Posts: 644	Re: Ca'nt get it down pat(tuning) ps.. post some pics of your setup.. id love to see it __________________ Phil Underwood My Turbo Buick