High boost and low timing... or...
Thread Starter
TECH Resident
Joined: Jan 2004
Posts: 832
Likes: 0
From: Castro Valley, CA
High boost and low timing... or... Please predict the two dyno curves for me from 3000-6500 rpm, valued experts: on a front-mount T67 (A/R 0.81), A2A intercooled, 346 ci w/-8 cc pistons, AFR 225's 72 cc. 60 lb injectors; plenty of fuel.
Setup 1: 15.5 psi boost, 12 degrees timing
Setup 2: 10 psi boost, 20 degrees timing
Assume that each setup is tuned to proper AFR.
Theoretically, what curve profiles would you expect on a dynojet?
Thanks in advance for your opinions.
Setup 1: 15.5 psi boost, 12 degrees timing
Setup 2: 10 psi boost, 20 degrees timing
Assume that each setup is tuned to proper AFR.
Theoretically, what curve profiles would you expect on a dynojet?
Thanks in advance for your opinions.
TECH Senior Member
Joined: Nov 2001
Posts: 10,341
Likes: 1
Why would you only run 12 degrees timing with 8.8:1 compression and 15.5#'s boost?
What octane would you be running?
With proper timing and your comp ratio 15.5 pounds boost should make 85-100 plus more RWHP than 10#'s imo
What octane would you be running?
With proper timing and your comp ratio 15.5 pounds boost should make 85-100 plus more RWHP than 10#'s imo
14-15 psi with 15-16 degrees of timing is all I run with 104 unleaded @ 9.5:1.
Honestly going from 13 to 18 degrees of timing makes little difference in my car as far as ET/MPH, air/fuel makes a way bigger difference.
The more boost with less timing will definately make more power, my same combo ran 10.40@129 with 10psi and 22 degrees of timing. Cant help you with dynojet curves
Honestly going from 13 to 18 degrees of timing makes little difference in my car as far as ET/MPH, air/fuel makes a way bigger difference.
The more boost with less timing will definately make more power, my same combo ran 10.40@129 with 10psi and 22 degrees of timing. Cant help you with dynojet curves
Originally Posted by kp
The more boost with less timing will definately make more power, my same
Originally Posted by fletchls1
I thought it was the other way around? With boost dont you make more power advancing the timing, and nitrous you make it retarding the timing?
Trending Topics
Originally Posted by kp
That depends on so many factors, combustion chamber, dome design, inlet temp, fuel used etc. You retard the timing to avoid detonation with both. Naturally with higher cylinder pressure (more boost or nitrous, whatever you prefer) you need to reduce the timing depending on fuel used. I could probably make more power running C16 and 5 more degrees of timing but on 104 unleaded it may not be a good idea..
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Originally Posted by LTLHOMER
How about more boost and more timing?
Originally Posted by 67Firebird455
Then you end up like me... nuclear f-ing meltdown. Poor car. With the 8.8:1 I would run at least 16-18 degrees at 15# boost, assuming your intake air temperatures don't sky rocket with the increased boost. There are a lot of variables that must be filled in. No meth to cool the charge? I am planning on running about that same compression with the new motor, was also thinking meth (better safe than sorry) with more timing, and the same amount of boost. You should be perfectly fine as long as 1 your IAT and EGT don't fly through the roof and cause meltdown. =)
I have the same compression, same boost, but 6-7 more degrees of timing.
Yes sir, I was on california famous oxygenated 91 octane fuel. That was on the stock shortblock with 97k on it, had oil come in the top end when the stupid body shop ran the car without the mocal scavenge pump 12v hooked up and it ended up detonating big time after that and grenaded. I was 16 and would KR down to 12.5 under boost. Knocked the boost down to 5# and that's when the motor came apart.
Thread Starter
TECH Resident
Joined: Jan 2004
Posts: 832
Likes: 0
From: Castro Valley, CA
I was mostly curious if running the low timing/higher boost (setup 1 above) could result in the turbo running out of steam at about 5000 rpm... sounds of the turbo maxing out, torque dipping off, etc. Making good rwhp and rwtq at that point, but you wouldn't be able to use the motor above 5k without damaging something, I think. This is on 91 octane Cali gas (dammit). I will be running methanol, but I want a good safe tune prior to crossing that bridge. On the plus side, I'm pretty certain that there aren't any leaks and that the FAST intake is just fine with over 15 psi...
Or are there other more probable causes for a dyno graph that looks great but just ends too soon?
Or are there other more probable causes for a dyno graph that looks great but just ends too soon?
had oil come in the top end when the stupid body shop ran the car without the mocal scavenge pump 12v hooked up and it ended up detonating big time after that and grenaded.
That must have sucked.
Jim
