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Discussion Starter · #1 ·
I run an 8.5:1 427 SBF with twin 67mm PT turbos on a glide. I know there is some redundancy here between low compression, E85, and 50/50 water/meth, a/a intercooler and relatively low timing. The E85 tested right at 70% ethanol.

The car made 1000/1000 on the dyno without meth/water on a 65 degree day this spring. MAT climbed about 30* each run at 20 psi and 18* total timing. My MAT sensor which gives nearly instant results placed top dead center of intake tube in the middle of the intake climbed from 60s to 90s each run.

I sense then put a progressive meth water kit controlled by holley on.

I made it to the strip the other night and was kind of disappointed and question whether the meth/water is actually hurting.

It was 73* outside and my MAT was showing 103* after the burnout, I didn't start datalogging until after the burnout. The car ramps up fast and made 20 psi and 100% injection meth water nearly the whole run (2 m10s/ 1260 flow I believe). The temp spiked a bit during 2 step and held under 112* the entire run. It didn't lower but it didnt climb. Total timing still at 18* for 20psi

9.6 at 145 with 3700 lb car with me. 60' was 1.58. Was the best of 2 runs. Raised 2 step rpm and ramped up my boost/time curve. (probably could almost get rid of that now.)

I know there's a lot to be made up in my 60 and probably my rear end gearing of 3.25. My goal has always been to make this an 8 sec "street" car.

Are these the results that I should be expecting? Was told I could safely run 22* and 22psi. So probably 6 more degrees of timing at 20.
 

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What is the engine combo?

I know my tw heads don't want/need a lot of timing. Made best power at 15psi and 18*timing (20* after peak torque). Didn't detonate nor make any more power by adding any timing.
 

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What ignition system and plug gap? On one car i used water meth, it seemed to want tighter plug gap and tiny bit more timing since the water kinda slows down combustion and meth richens things up, so main Gas fueling i had To lean out to compensate for the meth fuel addition.
I also dont think you need water meth at those temps and compression ratio on that boost level. Did you make any hits without water meth?
 

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Where is water/meth injection point in relation to temp sensor?? That's a tricky number to trust or God forbid tune by other than maybe a safety input. I run 100% methanol but couldn't tell you what the IAT values are because I don't even look at them. There is no way to actually see what is going on in the chamber which it what actually matters. I can't measure it there, I can't change it so I don't worry with it. I do have EGTs but don't tune by them they mostly keep tabs on all 16 injectors. Read the plugs, they are the only witness to the combustion event. Really disect the time slip especially back half split. It is telling you more about the engine and power output than the early times where chassis, converter, traction etc all cloud the information. If I felt I had to use IAT it would be before anything is added to the air stream. There are four(4) different liquids going thru phase change(latent heat of vaporization) prior to/during combustion that all have different temps that this happens so don't try to read temps with all this going on. Just my $0.02
 

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Discussion Starter · #7 ·
What ignition system and plug gap? On one car i used water meth, it seemed to want tighter plug gap and tiny bit more timing since the water kinda slows down combustion and meth richens things up, so main Gas fueling i had To lean out to compensate for the meth fuel addition.
I also dont think you need water meth at those temps and compression ratio on that boost level. Did you make any hits without water meth?
I am running holley smart coil system and if I remember right I gapped them at .23. The holley efi seems to do well in hitting target AFR's even with the water meth. I only got 2 runs and did not try a hit without the water meth.
 

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Discussion Starter · #8 ·
Where is water/meth injection point in relation to temp sensor?? That's a tricky number to trust or God forbid tune by other than maybe a safety input. I run 100% methanol but couldn't tell you what the IAT values are because I don't even look at them. There is no way to actually see what is going on in the chamber which it what actually matters. I can't measure it there, I can't change it so I don't worry with it. I do have EGTs but don't tune by them they mostly keep tabs on all 16 injectors. Read the plugs, they are the only witness to the combustion event. Really disect the time slip especially back half split. It is telling you more about the engine and power output than the early times where chassis, converter, traction etc all cloud the information. If I felt I had to use IAT it would be before anything is added to the air stream. There are four(4) different liquids going thru phase change(latent heat of vaporization) prior to/during combustion that all have different temps that this happens so don't try to read temps with all this going on. Just my $0.02
The nozzles are down stream from the intake about 2 feet. The sensor is right at a turn going down into the intake. I was told that intake air temps in the 130s was kind of a limit. That was on pump gas and not e85 I believe. As I mentioned above the holley system is pretty good at adjusting and hitting target AFR even when I randomly throw the stuff at it.. Thankfully
 

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Discussion Starter · #9 ·
Don't worry about the temp on e85......145 on 20psi on with 427 does not sound right
I also agree about MPH seeming a bit low. When I get home I wanted to dive in a little bit into the datalog and driveshaft speed and compare to RPM and gearing and see how much transmission slip I have amount a few other things. I know with my current gearing I hit right 6000 rpm at the end of the 1/4. 7000 is my red line.
 

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Water/meth injection doesn't do anything for you unless need it to run more timing.

You didn't mention your camshaft specs so it's hard to say what is a reasonably MPH. I have a turbo 363" SBF and with 18lbs boost it runs 8.8x at 158mph or so with 100 deg F inlet air with E85 in a 3550lb car.
 

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It still gained 30mph out the back . So its making power , just not fast enough .

How much boost is it leaving on and how fast does it make it .

What RPM are you crossing the stripe . Im guessing 6000 if its a 28" tire ? Are you sure its 5% slip ?

Can you post the data log with boost , rpm , fuel pressure , timing , ect
 

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Discussion Starter · #16 ·
It still gained 30mph out the back . So its making power , just not fast enough .

How much boost is it leaving on and how fast does it make it .

What RPM are you crossing the stripe . Im guessing 6000 if its a 28" tire ? Are you sure its 5% slip ?

Can you post the data log with boost , rpm , fuel pressure , timing , ect
I left at about 5 psi and 4000 rpms. That run my boost over time curve was set at about 1 sec till full boost. I forgot to hit the data log on the second 2nd run (Already reset it to auto trigger when the line lock is triggered for the burnout now).

The first run I did hit the datalog and I had left at 3500 rpm on 4 psi and it ran a [email protected] 145 with a 1.588 60'. My boost matched my boost over time graph almost perfectly. 2 seconds to hit 20 psi. No dips or studder just followed the targeted boost.

I run a 27" tire and when I saw the 1/4 mile light I let off at 6080 rpms according to datalog. so probably 5900 rpms. It still puts me right at 5% slip or less.

I'm away at military training for the next couple days but will post my 9.7 datalog run.
 

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My advice is to take a few steps back in the process especially if you want to be your own tuner. Make some complete passes at 5psi and tune it/optimize the performance at that level. Then progress up in steps doing the same thing until you get back to 20psi. This is how you learn about tuning and what your engine likes. Back in 2008 when I first built my car I made dozens of passes at lower boost levels.
 

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"left at 3500 rpm on 4 psi and it ran a [email protected] 145' Christ you v8 guys have it so easy....... to run 9's with my 4 cylinder 4 speed it takes 35psi boost and 5000RPM launch.
Oh yeah. Leaving on 5psi and running a max of 10psi boost my 363 sbf in a 3550lb car runs 9.7x at 140. And that's shifting at 6800.
 

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I left at about 5 psi and 4000 rpms. That run my boost over time curve was set at about 1 sec till full boost. I forgot to hit the data log on the second 2nd run (Already reset it to auto trigger when the line lock is triggered for the burnout now).

The first run I did hit the datalog and I had left at 3500 rpm on 4 psi and it ran a [email protected] 145 with a 1.588 60'. My boost matched my boost over time graph almost perfectly. 2 seconds to hit 20 psi. No dips or studder just followed the targeted boost.

I run a 27" tire and when I saw the 1/4 mile light I let off at 6080 rpms according to datalog. so probably 5900 rpms. It still puts me right at 5% slip or less.

I'm away at military training for the next couple days but will post my 9.7 datalog run.
Wow, you might have some left in this. Leaving at 4psi with a 1.58 60' and 9.76 at 145(!!!) Yikes - 145.

In this thread you've hit on all of my issues that I need to improve as well, but my issues are a bit worse. I'm on a much lower budget setup, but most of the same principles apply I believe. I'm on e85 (80% ethanol) with 50/50 meth mix at 20psi. My IAT's climb to 190 from a start of 100 on the hit. I launch at 10psi to run a 1.55 60'. I'm working hard over the winter to decrease the IAT's - I'd like to go without the meth injection if possible.

I'm curious of your 5% converter slip number. What trans/converter combo? I'm at 11% with an unlocked 80E with a single billet 9.5" Freakshow. How are you calculating converter slip- 5% is fabulous imo.

I take 1.5 seconds to get from 10psi to 20psi.


I think you're concern of IAT's is not a concern. You need to figure out to get it off the line. It looks like you could be into 1.3-1.4 range easily and probably better.

Would love to see a datalog, tune and hear what your trans/converter is. Topfun is a goto source of info here AFAIC. His advice of making runs at low boost is an excellent one. Just need track time to dial it into the maximum amount of go. Probably an advantage of being in Florida lol. Track time here in upstate NY is demanding for test-n-tune all summer and impossible this time of the year.

Good luck - Jim
 
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