Ordering pistons what compression?
- Thread starter norbs
- Start date
It's your wallet. Good luck.
You are correct, I will attempt also to find out which cylinders are knocking, by upgrading my fast dash to 1000 frames per second, if it does not work I'll find out in a hurry looks like. I am still going to go for 9.5 to 1, I may have to use alky now though.
Using the alky with the pump gas is a for sure. The sim runs with the pump gas look ugly. Don't run low on that alky. You gots no safety cushion, except for your JS box.
That is a valid point however, I can rig up something in the XFI to prevent boost from rising without alky pressure pressure present, I will have to come up with something for sure. On another note I will be changing the rear axle ratio to 3.89, this might help also. What do you think?
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Norbs,
I'm glad to see your running something a little out of the box although I don't think it is as sensitve as Don would make it seem. I'm sure Don would agree that you don't go faster doing what everyone else has done.
Allan G.
A lower gear will allow rpm to rise quicker, possibly allow boost to rise quicker. As long as you have a good boost control system, you'll be OK. You certainly can't afford to have a boost spike when running on the edge.
I wouldn't call trying to skirt the limits of one's static CR, thinking out of the box. That's a very common occurrence by those that just don't know better. I myself was guilty of the same thing, and have the scrap metal to prove it.
Well, no one can ever argue that learning by doing is not a powerful way to discover a better way of doing something.
The way I look at it is, there are a lot of tuning parameters that can easily be played with to obtain a target performance level. There are so many of these tuning parameters that can quickly be changed if it's found that you're running too close to the edge.
Static CR is basically a tuning choice. Unfortunately, it's a tuning choice that can't be quickly changed. Most would not bother to change a static CR that they've found to be unacceptable until a major mishap occurs. You are basically stuck with the static CR you choose. For a street application, why would you choose a tuning parameter that is so close to the edge, and on top of that, so immovable, when you have other tuning parameters that are so much easier to deal with and change to come to the same performance level?
Static CR is basically a tuning choice. Unfortunately, it's a tuning choice that can't be quickly changed. Most would not bother to change a static CR that they've found to be unacceptable until a major mishap occurs. You are basically stuck with the static CR you choose. For a street application, why would you choose a tuning parameter that is so close to the edge, and on top of that, so immovable, when you have other tuning parameters that are so much easier to deal with and change to come to the same performance level?
Pushing the static CR limit with a n/a engine is one thing. Pushing it with a turbocharged engine seems silly to me. There are so many options available to deal with turbo spooling.
Static CR does not make or break a turbocharged engine, by no means. In fact, IMO, it's the least important parameter.
Static CR does not make or break a turbocharged engine, by no means. In fact, IMO, it's the least important parameter.
I'm afraid, Norbs, that what you'll end up with is an engine you'll be scared to push on. It's a completely different state of mind when you're pushing on an engine that has a clear limit, compared to pushing on one that proves to be almost impossible to blow up.
I'm afraid you right, however I want the engine to be responsive OFF boost, I do not like lag at all. I'm limited to converter because of the overdrive I will not be able to loosen the converter at all, right now stall speed is 2500 off boost which is perfect for driving around. Is 9.5 to 1 going to be that risky?
750H.P.V6
Brutal 6 Racing
- Joined
- Sep 4, 2001
Don,
I know you're concerned about running a 9.5 to 1 compression ratio in a street car but you're aware that GM builds factory supercharged engines for the Cadillac CTS V and the new ZL 1 Camaro that have a static compression ratio above 9 to 1 don't you? I know it's not a Buick but I'm sure GM did their R & D prior to deciding on going with that compression ratio in lieu of something lower. These engines come with a 100K warranty also.
http://allenginelist.com/cars/supercharged-6-2l-lsa-v8-2013-chevrolet-camaro-zl1-engine-specs/
Neal
I know you're concerned about running a 9.5 to 1 compression ratio in a street car but you're aware that GM builds factory supercharged engines for the Cadillac CTS V and the new ZL 1 Camaro that have a static compression ratio above 9 to 1 don't you? I know it's not a Buick but I'm sure GM did their R & D prior to deciding on going with that compression ratio in lieu of something lower. These engines come with a 100K warranty also.
http://allenginelist.com/cars/supercharged-6-2l-lsa-v8-2013-chevrolet-camaro-zl1-engine-specs/
Neal
I'm sure that 9+ to one in a modern supercharged engine doesn't necessarily translate to a V6 designed in the 70s, but it sounds encouraging. Is Norbs going to be upgrading the design of the Stage II V6 to the level of modern engines now?
Is the gasoline that much better now than it was in the 80s? Or, is it simply the design of the engines? If it was better to run high compression with a turbocharged Buick V6, I don't understand why Buick didn't do it in the 80s. Did Buick not do the proper research back then?
Heck, if a modern engine can put up with 9+ to one on the pump gas of today, then why couldn't a Buick V6 do 10+ to one with C16 gasoline? I think it's worth a try, Norbs. Let's see how that works out. I'm sure off boost performance will be bitchin.
I have to ask. Are these modern supercharged engines boosting 22 psi on pump gas like Norbs is planning to do?
Are you fellas looking out for Norbs best interest? Or, are you just curious to see what happens to his machine when he takes your advice?
Are you fellas looking out for Norbs best interest? Or, are you just curious to see what happens to his machine when he takes your advice?
This thread has run it's course. You can debate all you want. Sim this sim that. Higher CR increases power everywhere and increases drivability over lower compression ratios. 9.5:1 on this engine which will be running 116 octane is not a high risk for his intended boost level. The engine will flow about 100 lbs/min@30psi. With intake duration in the mid 230's it will peak around 6000rpm. Have a nice day
750H.P.V6
Brutal 6 Racing
- Joined
- Sep 4, 2001
Don,
You seem to jumping around a bit. What I was trying to get at is that 9.0 to 9.5 to 1 static compression is not outlandish for a forced induction application. The LSA motor I posted a link to has a lot of similarity to a Stage II motor as it relates to bore / stroke and even the heads are similar. To be truthful a Stage II head is most like an LS7 head but bears a close resemblance to the LS3/ L92 head which is on an LSA motor. Also I might have missed it in the thread but where were we talking about running 22 psi boost on pump gas?
Neal
You seem to jumping around a bit. What I was trying to get at is that 9.0 to 9.5 to 1 static compression is not outlandish for a forced induction application. The LSA motor I posted a link to has a lot of similarity to a Stage II motor as it relates to bore / stroke and even the heads are similar. To be truthful a Stage II head is most like an LS7 head but bears a close resemblance to the LS3/ L92 head which is on an LSA motor. Also I might have missed it in the thread but where were we talking about running 22 psi boost on pump gas?
Neal
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