OTT308

Hey there, hopefully someone can tell me the theory or their experience on tuning with meth injection. NO INTERCOOLER

My combo:
-383 LS1
-stock 241 heads
-8.5:1 CR
-Edelbrock Pro Flo intake and Throttle Body
-S475 T4 83mm log manifolds
- 160deg thermostat
-60lb injectors
-two 044 pumps
-progressive meth kit 3 nozzles (after turbo, before throttle body)
-powerglide and 9 inch diff
-off the shelf comp cam 285LSR
-pump gas
-B8EFS spark plugs

On the dyno on pump gas the tuner finished up with 13 deg timing and 10.2:1 afr. This achieved 430rwhp. There was no sign of knock but he wanted to leave the tune there. Ambient temp was 86 deg farenheit and IAT were up to 170 deg. He did one run without the meth and the IAT were the same???? I am running no intercooler just a meth inj kit with 3 nozzles and 100% meth. I thought it could go a little better than it did??? What sort of afr and timing is everyone else running????

dville_gt

iTrader: (5)

couple of things, why so cold on the plugs, why was he tuning to 10.2:1 (that is very rich), and there should have been a big drop in IAT on 100% meth, are you sure it is coming on and what nozzle(s) are you running? try an 80/20 mix of meth/water and make sure you have the nozzle sized correctly.

Bloodbath

is there a possibility the iat sensor is getting heat soak from the manifold itself.
as you said mark

OTT308

First thanks for your input.

I think the tuner was scared to lean it out with no cooler, also the IAT were up at 170deg. I would personally like the AFR at roughly 11.0 (with meth). I have 2 #10 nozzles and 1 #15 nozzle. I am certain it is coming on as the AFR went from mid to high 11 down to 10 when meth comes on. Also the tank is emptying. I also spoke to Rodney from AIS today and he also said to try an 80/20 mix. One thing is placement of my IAT sensor, i have now changed it on a thinner part of the plenum as i dont think it was getting much air flowing past it and therefore getting heatsoke from the plenum? Also i put B8EFS plugs in thinking i would be turning boost up. What plugs are popular up to 6-700whp? I would like to run approx 11.0 AFR with the meth on, what sort of AFR does everyone else aim for? NO INTERCOOLER, PUMP GAS, 15psi boost

Chris@CBR

Is there a chance the meth wasn't working to start with?

OTT308

Unfortunately i am very positive it was working the whole time. As at the very start there was a tiny leak on one of the push lock fittings, and also the AFR would change dramatically under boost. I have changed the IAT sensor location as Rodney from AIS is positive the IAT should be roughly 100deg farenheit (if not lower) going off the AFR change and nozzle sizes and current boost pressure. As i saw absolutely no change in IAT when meth was activated?

The Alchemist

iTrader: (19)

So you made 430hp on a 383 with 15psi? If that's true, then something is definitely up?

383mazda

iTrader: (2)

Meth will not really cool things down until inside the chamber during combustion - that's where it helps; temp and pressure start to rise as piston comes up, when meth starts to vaporize it soaks up a lot of the heat being generated inside the chamber.

You can tune much leaner - 12.5 or so with meth, you do not need cooling effect of extra fuel when you're using meth. You're wasting fuel and losing some power. Meth cools MUCH better than fuel which is why people run it in the first place rather than running pig rich to avoid knock. Warning - if you tune for optimum power with a better AFR and then run out meth, under WOT you will hurt things...

Now you've got the tough question - lean out your current mixture or throw more boost at it

Old Geezer

iTrader: (3)

Any EGT's recorded??

OTT308

Yeah something definately is not right. Not many people in Australia use meth injection.

383MAZDA
This time I am going to tell the tuner what AFR i want under boost. I will lean it out at the current boost setting as I have a 2 bar map sensor. Surely there is a heap of power in leaning this out? What sort of power should i expect with this boost and cubes etc?

OLD GEEZER
This time on the dyno with the meth we did not record EGT. When we tuned it originally it had 10psi boost and the EGT would see as high as 550deg celcius. (this was with no meth). This also produced the same hp

PRAY HRD

iTrader: (119)

unless you're dead set on who you're using for a tuner, i'd give these guys a call and have a chat with 'em! 430 rwhp is a sign of something definitely not working right.

http://www.cvperformance.com.au/

Johnv

My 383,10.2:1 comp, 16psi boost, intercooler, pump gas and meth makes 700 rwhp,
11.0 afr on meth and 17 deg timing

Bloodbath

good numbers, that tc78 must be screaming! that thing would be a weapon on the street.

OTT308

I would love to use CV Performance!!! I am contemplating buying HP Tuners and doing it myself?

OTT308

That is some good figures dude!!! I think mine should be making roughly 550hp with 15PSI boost considering i have no intercooler? The AFR and timing you are running is what i think mine should be tuned for at 15psi (ballpark anyway)

How much power without meth??? What AFR and timing without the meth??

Bloodbath

buy hp tuners already ferg! then come tune mine!

Johnv

I run 11.8 afr and 12 deg timing on Bp ultimate.
Will take another 5 deg timing with meth and makes an extra 50-60 Dahl
I have much higher compression than yours but do have a 600x300x100 intercooler.(I run straight meth, 2 jets and a 250 psi pump)

Johnv

Just put a turbonetics T76 thumper , same size exhaust wheel, but huge compressor cover.
It's a bit of a handfull on the street, will break the tyres loose at 100mph in 4th..

OTT308

Some progress!!!

Back on the dyno with an 80/20 meth mix and IAT sensor relocated to just after the TB. Seems to be working great now, IAT were approx 110deg (20 above AMB). Tuned to 11.0:1 and gained 30hp. (still a low figure for 15PSI) I started to suspect the converter???
The engine rpm was 6000 and wheel speed was 130mph, put these figures into an online calculator with the 2.75 diff gears and it comes up with 37% converter slip!!!!!!

Big thanks to Rodney from AIS