s14 sr with built head, 11:1 or 9:1 comp?

[TEALSQUEAL]

I'm ordering my pistons for my s14 sr build. I am debating on the compression for the pistons. I'm using a standard headgasket, and the head has BC 272's from a previous build. it is an s14 so I am trying to account for the kicking in and if the valves will contact the pistons with the 11:1 and the 272's. anyone tried this setup?

[jr_ss]

Do they even make 11:1 pistons for the DET? Personally, it's not a Honda motor, nor does it breathe like one. Get the 9:1's and enjoy your newly found transient response.

[TEALSQUEAL]

Yes CP makes them. I've ridden in an s13 sr'd car with them, and they did very well low end and added some power throughout the range.

[stacksondeck]

Lol 11:1 CR and 10psi knock threshold..


Probably a reason you can't find one person running that high of a CR. Unless you plan on running ethanol or c16 it would not be a wise move.

Edit: even then it would still be dumb..

[ultimateirving]

11:1 and e85, run low boost on a t28 and that thing will be a monster. You will have insta spool and a great amout of power!

[stacksondeck]

Is a t25 not insta spool enough as is?

If you need that kinda low end grunt you need 4 more cylinders.

[fliprayzin240sx]

11:1 and e85, run low boost on a t28 and that thing will be a monster. You will have insta spool and a great amout of power!

11:1 on a turbo engine? Fuck, if you have to run that high of a damn compression, he might as well stick the KA back in there.

[TEALSQUEAL]

You guys make me laugh. Actually it is a E85 car. A friend of mine locally ran the 11:1's in his s13 sr making 400whp on a hks equivalent to a 2871 with small housing. It was VERY rowdy. I do plan to sell the car in the next year so I will do the 9:1's so the future owner can run e85 or pump gas :-(.

[stacksondeck]

If we humor you with our knowledge then why the fuck do you ask for it? Not one person on this forum runs 11:1 only to make 400hp..

There is a whole damn thread of people making over 400whp with 8.5:1 CR and PUMP GAS with 2871's so I wouldn't brag about ole dudes car on ethanol and 11:1 CR with a 2871 making that kind of power. Something is wrong with his car or a retawd must have tuned it.

If my engine was switched to e85 and 11:1 CR I would need sleeves and 1/2" headstuds due to how much more power my car would make. 460whp on pump at 8.5:1 to well over 600whp with the switch on fuel and CR. 400whp is a joke on e85 with that high of compression..

[Tom N]

Everyone is so scared of high compression. I ran 10.1 for years with a GT35r making 650hp on pump gas with alcohol injection.
Real simple if you plan to run regular pump gas stay around 8.5-9.0
If you will be running E85 or injecting a lot of alcohol and very importantly are a good tuner then you can go higher in compression.
Some of the fastest turbo 4's out there run 13.1.
You will make more power with 11.1 if you are set up for it and can tune.

[TEALSQUEAL]

Sometimes it's about how the area under the curve is, not how it peaks. This car is being built and used primarily for road course and other similar broad powerband driving. This thread was mainly asking about if anyone is running these pistons with the 272's in an s14 sr. I am worried about piston to valve clearance not how much power ill make. I will size my turbo appropriately for my goal of 450whp and maximizing the efficiency of whatever turbo I match it to. Thanks for your conjectures

[jr_ss]

Why don't you do the research and figures on clearances. They have all the information you need in the FSM and the piston manufacturers website. No one but a handful of people in the DET world runs 11:1 pistons.

You don't need 11:1 pistons to reach your punitive goals.

[TEALSQUEAL]

I can't quite tell if you are referring to my goals as being not much or what? The cost return on my time to do the appropriate research was less than simply posting a thread to get a response from "experienced" people. I know you jr_ss from nrr and expected a little more.

[jr_ss]

I honestly don't have the answer and was trying to point you in a tried and true setup. I wasn't trying to come off as an ass Dave. I was just saying that the information for the calcs are there, but my best guess would say that 11:1 pistons are going to be too aggressive for the 272 cams and the DET altogether. Generally speaking, setups running those comp ratios are on motors/heads that flow extremely well, Honda's, DSM's, etc. As I've stated before most people in the DET world do not run those comp ratios unless it's an all out race engine.

400-450whp isn't a huge power goal. Now-a-days it's pretty tame on the SR. You know as well as I do Zilvia is not the place for this question and I see you've got a post up over at NRR.

[TEALSQUEAL]

Agreed that's the reply I expected, and thanks for that. The setup did well on an s13 with s3's just as a reference, until it dropped a valve due to storage after two years. After looking at the s14 with the advance still intact and 272's it doesn't look safe with a stock head gasket.

Punitive btw can be construed as condescending from its definition depending on how you consider he context. I'm sorry I considered it as such. Btw I'm jealous of your VE fun.

[jr_ss]

No worries man, poor choice of words...

I'm jealous of the VET too, I'm still trying to get it finished. Work and other things have cut into my time to finish it. I'm slowing down so hopefully I can finish the few items left on the list.

Good luck on your decision, if you plan on selling anytime in the future, you're going to have an easier time selling it with 9:1's in it.

[TEALSQUEAL]

Agreed. If you need an s13 sr parts for your build hit me up. I have a few extra bottom ends.