Will this run on pump gas...
Thread Starter
Joined: Nov 2001
Posts: 7,303
Likes: 4
From: Delray Beach, Fl.
Will this run on pump gas... 11.4 SCR
9.1 DCR
I'm running a small cam 214-222 559-566 115+4..It wont bleed off any CR with my ported heads and should make TQ out the whazoo..I just wann know if it'll run on 94 Octane...
What timing should I shoot for too
I was thinking 25 Total if I dont see KR...
9.1 DCR
I'm running a small cam 214-222 559-566 115+4..It wont bleed off any CR with my ported heads and should make TQ out the whazoo..I just wann know if it'll run on 94 Octane...
What timing should I shoot for too
I was thinking 25 Total if I dont see KR...
TECH Regular
Joined: Oct 2005
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If I was tuning this combo, I'd dial it in first with 94, aiming for Lean Best Torque fuel and all the spark it needed, then go for a couple of degrees more, just to see how octane sensitive it was. If all is well, richen and back off to your personal comfort/power level and you're done. If the power was still increasing when KR started in, dump in some 100 unleaded or a good octane booster and see what you're missing.
If it looks like you have to give up too much to stay knock-free on 94, try retarding the cam 2-3 degrees to reduce DCR and repeat.
Since there has been a ton of dialog here on maximum acceptable DCR, I'm sure we'd all like to hear how you make out!
If it looks like you have to give up too much to stay knock-free on 94, try retarding the cam 2-3 degrees to reduce DCR and repeat.
Since there has been a ton of dialog here on maximum acceptable DCR, I'm sure we'd all like to hear how you make out!
Last edited by MadBill; Dec 10, 2005 at 10:01 AM.
Originally Posted by fastta
Easily. The best measure of the ability of a motor to effectively run on pump gas is DYNAMIC compression ratio and not static. Given this, at 9.1, 94 will be more than adequate.
OTOH, if your quench is dialed in to right about .035" then you will be less prone to detonation so you may get away with it.
Nate
Launching!
Joined: Jan 2004
Posts: 201
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From: Clearwater, FL
Originally Posted by Nate_Taufer
I don't know about that. 9:1 DCR is the max I shoot for in a LSx based engine. You may be able to get away with a little more but for longevity of the motor and resistance to detonantion I would suggest shooting for around 8.8:1 or a little less to stay in that safe range.
OTOH, if your quench is dialed in to right about .035" then you will be less prone to detonation so you may get away with it.
Nate
OTOH, if your quench is dialed in to right about .035" then you will be less prone to detonation so you may get away with it.
Nate
, but you just have to spend a little extra time dialing them in.Another thing to consider is that in almost all cases, the posted pump gas octane ratings are actually slightly less then what they actually are. Our 93 here in TX is actually 93.3. Just guessing, I would say that 94 is likely to be 94.4 or close to.
Thread Starter
Joined: Nov 2001
Posts: 7,303
Likes: 4
From: Delray Beach, Fl.
I was told tuning would be in the 20 to 23 Degree range,Am I giving up power if I go this route.I mean would it be better to go 62CC and a .045 Gasket and run say 11.2CR but have a quench of .038..
My setup is 59CC with a GM MLS .056 which gives me a quench of .050 which is what Duttweiler suggests for most street cars...
My setup is 59CC with a GM MLS .056 which gives me a quench of .050 which is what Duttweiler suggests for most street cars...
I've also seen several LT1's with roughly 12:1 SCR and mild cams running fine for years on 93.
This is about the only reason you can run higher SCR/DCR than a Gen I SBC. The LS1 can run higher (~11.5-12.0/~8.8-9.0) SCR/DCR because of the "fast burn" chambers.
Just some points to ponder.
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Thread Starter
Joined: Nov 2001
Posts: 7,303
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From: Delray Beach, Fl.
Yes but a high quench and my heat soaking GTO engine bay has me scared
I think I'm going to buy Patriots new or Darts new with a 62CC chamber and make SURE I dont detonate....I was only saving 200 on the used heads over new so for me I think going Dart or Patriot is the better way and then get the Chamber that I want 62 to 64...
I think I'm going to buy Patriots new or Darts new with a 62CC chamber and make SURE I dont detonate....I was only saving 200 on the used heads over new so for me I think going Dart or Patriot is the better way and then get the Chamber that I want 62 to 64...
Last edited by JS; Dec 11, 2005 at 09:18 AM.
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I agree with MadBill.
Sometimes it comes down to something simple as engine coolant temp, or polishing everything in the chamber area.
If you find that you want to make more power with more spark advance you could run the engine at a cooler temp with cooler plugs. People have been doing it for years instead of running race gas.
Sometimes it comes down to something simple as engine coolant temp, or polishing everything in the chamber area.
If you find that you want to make more power with more spark advance you could run the engine at a cooler temp with cooler plugs. People have been doing it for years instead of running race gas.
