S13 Questions

Does anyone know the 1/4 mile times on a S13 Silvia "SR20DET". And what is there redline. And can I make a longer redline without hurting the motor? Or is it better to leave it the stock redline?

7500 is the stock redline, if you get rock arm stoppers, it'll rev to maybe like 8500, but I'm guessing there's some kind of rev limiter...

yeah you can get chips that get rid of the rev limiter but you don't want to go too overboard.. the sr, just like any other engine, can handle only so much rpm.. best thing to do would be to replace the internals cause lower compression internals will be able to handle higher rpms

1/4 mile is just over 14 i think on a red top

Lower comp rases rpm limit?

no, lower compression gives your engine the ability to handle higher rpms

Handle more boost, not handle higher rpm.

Both.

you learn something new everyday eh logik!!

Yeah, I guess ,but how does it allow the engine to rev higher? Less mass? Low comp pistons are smaller, so is that why?

does any one know of any one thats makes some performance chips.

jim wolf

Uhhh doesnt venom make a performance ecu? Maybe im just making an ass of myself, oh im back.

They do, but I dunno if it actually does anything.

aem makes something for the sr also

think about it.
8.5:1 @ 7000RPM
or
11:1 @ 7000RPM
which one will have less stress on the engine?

I guess, but less power with the 8.5:1

HKS makes limiter removers, I've seen them alot online

I wouldn't try to make the engine rev to high though, lower compression would up the rev but lower power which i think is a bad trade except maybe in drifting, where power isn't as major a concern, also wouldn't uping the boost up the compression rate overall thus defeating the purpose?

Maximum boost on 8.5:1 comp makes more power then max boost on 11:1 comp ratio.

Maximum boost on 8.5:1 comp makes more power then max boost on 11:1 comp ratio.

now you know what i mean. and the engine will be able to handle the higher rpm

No, 12psi with a 11:1 comp ratio will make more horsepower then 12psi with a 8.5:1, but with the 11, your engine will blow in a few minutes or running it, lol. What I meant is that you can run 30 psi on an 8.5:1 and only like 10 on an 11:1 engine, so the 8.5 enigne will make more power. (these numbers aren't real, they are just an example, but the point stand, so don't flame me.)

yeah yeah that makes sense i just had them backwards.. its 12:50 and i had turkey leftovers tonight so i'm a little groggy.. time for bed

Yeah, it's same time here and I'm just cooking myself some KD and getting ready to watch some shitty late night info-mercials lol.

hey those infomercials arent shitty they are informative and they make me realize that i maybe a pathetic person for watching them but im not as pathetic as people who actually order the shit being sold on the info mercials. the only thing worse then info mercials is watching fishing and the onlything worse then watching fishing would be if you were a fishing show editor and had to watch all the " unexciting" parts that were filmed during a day of fishing and i have no clue why i started talking about this so ill stop

Yeah, Chef Tony rocks....actually, I was thinking of trying one of those get rich quick schemes, I mean it's like 30$ for starting and the people who talk make like 6000$ a week!!! Ok, I'm kidding, well half-kidding, I know those people are lying, but I still wanna try, like the Greatest Vitamin In the World, the pill is probably a placebo, but if I can get rich by screwing people over, I don't care.

hey ill be happy as long as im not editing a fishing show or it would also suck to write a script for a fishing show

uhh isnt the main thing limiting how high an engine can rev in the valvetrain? like the K20 can rev to 10,000 rpm with upgraded valve springs and retainers... i mean if you have a real long stroke that is going to be more stress with high revs but i think the real definitive problem you run into with over-revving is "valve float" (when the cam is turning so fast the valve cant make a full cycle before its pushed on again, so it kinda just stays open). so if you are getting that at a certain rpm, then changing to lower compression pistons will not take that problem away, and you still wont be able to rev higher, correct?

Low comp pistons will just lower the mass of all that moving shit inside the engine, which in term makes it rev easier, but yes, the main thing responsible for high revs is a good valvetrain.

Skip the chips if you can afford to do so. Get a reprogrammed ECU or piggy-back system. AEM, Greddy, Apexi, they all make an ECU or ECU addon system. Then you can make adjustments, even to your rev limiter.

they have some badass ECU's at flashoptions

Compression ratio isn't so important when it comes to RPMs. Sport bikes have like 11:1 and 12:1 compression ratios and look what they turn. Main factors in how fast you can spin your engine is piston speed and valvetrain. Stroke determines piston speed so obviously less stroke=higher rpms with appropriate valvetrain mods. SR already has low compression so with stiff springs and rocker arm stoppers, it should spin like a top. You could get fancy and have the entire rotating assembly balanced, knife-edge the crank, find the lightest pistons and rods, and get a really light flywheel. And think guys, what puts more stress on an engine? 11:1 compression ratio or 10psi of boost? Forged internals are already there.

SR piston speed @7500-4232ft/min
KA piston speed @7000-4410ft/min

The SR has room to grow.

Less mass, shorter stroke = high rpms.

But as you shorten the stroke, you lessen the amount of torque produced by the engine. Higher rpms can be acheived by increasing the strength of the valve springs, regrinding the cam to operate in the desired rpm range, strengthening the lower half and balancing all of the internals along with reducing weight. The flywheel has a lot to do with the rpm limit as well how quickly the engine will rev. Lower compression does not in it self allow for an increase in rpm levels. Motorcycles have higher compression ratios and rev higher. Formula One cars have HIGHER compression ratios and really rev high.

As far as compression versus boost. For a street driven car, lower the compression from, say 11.5:1 to 10.5:1 or 9.5:1. Your engine will live longer and prosper. Then you can up the boost and make good reliable hp.