13.5:1 Pistons

[woode]

Anyone done anything with the 13.5:1 forged pistons and FI with our cars?

I am getting ready to order parts and start building my spare engine in a few weeks and still haven't made my mind up on what direction I want to go with it. I am kind of over the 400hp on the street thing - I am going to get myself in trouble one of these days. Low end is fairly lacking, and top-end my dump pipe can be heard from 3 miles away letting every cop know to come give me a speeding ticket.

I was thinking of going for 13.5:1 pistons and a switching to a twin-screw supercharger on like 5psi for some really good throttle response and ~300hp on pump gas. I don't think I could run much more boost than that on pump with that high of compression, but if I can squeeze 300hp I will be good with it.

[stugray]

Heck 13.5:1 pfffttt Why not just go BIG! 15:1, 15 PSI boost, & nitro-methane!

[Ross]

I would recommend holding off if looking at the twin screw idea until the updated versions arise. You could also swap out to a smaller turbo, something in the gt28 gtx28 series or the b1 framed turbos from borg for quicker response and recirculate your dump tube.

[woode]

Originally Posted by stugray

Heck 13.5:1 pfffttt Why not just go BIG! 15:1, 15 PSI boost, & nitro-methane!

Thanks for making such a useful post.

Originally Posted by Ross

I would recommend holding off if looking at the twin screw idea until the updated versions arise. You could also swap out to a smaller turbo, something in the gt28 gtx28 series or the b1 framed turbos from borg for quicker response and recirculate your dump tube.

I have been following the bigger blower progress and that is part of what makes me want to go this route.. I thought about a smaller turbo, but having driven both I liked the partial-throttle response (if that makes sense) on a twin screw better.

[sw20kosh]

You are not going to want to increase the CR if you are planning on running the giant blower.

[xwd]

Yeah the 335 blower is going to make so much boost everywhere you aren't going to need higher compression. If it doesn't have a restrictor you may want to be running E85 all the time or lower compression...

I kind of want to build a 13.5:1/14:1 if I ever go built motor and basically run E85 all the time. Use this turbo: http://www.full-race.com/store/efr-t...3-turbo-3.html. The response of those turbos is pretty incredible due to how lightweight the turbine wheel is. I have a GTX2867R coming with my JDL kit but now that you can get the 7163 in a v-band turbine housing, it shouldn't be terribly difficult to swap. People on the STI can hit 25PSI by like 3000RPM with those turbos, and go from vacuum to 25PSI within about 400-500RPM above 3K. It's capable of hitting 500WHP on E85 with a very broad torque curve.


Of course your tires may hate you...

[stugray]

Originally Posted by woode

Thanks for making such a useful post.

Based on the two posts after yours , at least some of the posters understand where I was headed with my remark.

Either you want a full blown drag vehicle, or you are missing a critical piece of information regarding boosted engines...

If you want high CR AND a lot of boost, then your engine is one the verge of blowing up all the time.

By decreasing CR and giving you a greater range of boost, you have more margin for error in the tune.

[woode]

Originally Posted by stugray

Based on the two posts after yours , at least some of the posters understand where I was headed with my remark.

Either you want a full blown drag vehicle, or you are missing a critical piece of information regarding boosted engines...

If you want high CR AND a lot of boost, then your engine is one the verge of blowing up all the time.

By decreasing CR and giving you a greater range of boost, you have more margin for error in the tune.

I know how boost and CR works, thanks. I think it is you who should do some research. Decreasing CR lowers your effective CR allowing more boost to make up for it. This does allow for more HP at the expense of response and off boost power. but that isn't what I am ultimately after.
I never said anything about a drag vehicle or high boost. I don't know why you keep exaggerating what I am saying in an attempt to make me look stupid.

[20firestorm13]

The innovate kit, until a blow update which I think you said earlier isn't close to being able to hit 300 hp on pump gas. In it's current state it's barely hitting 300 on a dynojet on e-85 @ 12 lbs of boost, this is also with a 70mm pully. I haven't seen any kits with anything higher then about 305, unless there is another twin screw kit out besides the Innovate kit.

Originally Posted by woode

I know how boost and CR works, thanks. I think it is you who should do some research. Decreasing CR lowers your effective CR allowing more boost to make up for it. This does allow for more HP at the expense of response and off boost power. but that isn't what I am ultimately after.
I never said anything about a drag vehicle or high boost. I don't know why you keep exaggerating what I am saying in an attempt to make me look stupid.

[woode]

Originally Posted by 20firestorm13

The innovate kit, until a blow update which I think you said earlier isn't close to being able to hit 300 hp on pump gas. In it's current state it's barely hitting 300 on a dynojet on e-85 @ 12 lbs of boost, this is also with a 70mm pully. I haven't seen any kits with anything higher then about 305, unless there is another twin screw kit out besides the Innovate kit.

I am exploring building a higher CR motor with it. With the current kit I know I probably won't see 300, but by the time I am done building it hopefully the 335 will be available.

[20firestorm13]

I'm still running the stock internals on the engine and have been at 300. If you want to rebuild a motor for the sake of rebuilding then sure. I hope the 335 doesn't break my pocket book tho >.>

Originally Posted by woode

I am exploring building a higher CR motor with it. With the current kit I know I probably won't see 300, but by the time I am done building it gleefully the 335 will be available.

[Calum]

Originally Posted by woode

I am exploring building a higher CR motor with it. With the current kit I know I probably won't see 300, but by the time I am done building it hopefully the 335 will be available.

The 210+ might be of interest to you as well.

I'm glad to see someone exploring this idea. Good luck.

[JerryMichaels7]

custom or is someone making higher comp pistons?

[woode]

Originally Posted by JerryMichaels7

custom or is someone making higher comp pistons?

https://www.jepistons.com/Catalogs/S...aru/4ugse.aspx