High Comp And E85

[Simon-S14]

What are peoples thoughts on building a high comp motor with custom pistons with say 11:1 ratios or around that then running turbo and e85?

[TiTAN]

as long as its going to be dedicated e85 or race fuel the extra compression is going to make a massive difference to when the turbo comes to life.

[GTScotT]

Be careful of hotspots with comp that high.

Piston shape and combustion chamber will probably be crucial. This is what im working on to make my 10:1 SR cop BOOST.

[DVS JEZ]

E85 masks the det prone area due to the higher RON, But of course make sure the chambers are setup to suit.

[sneakey pete]

I believe that there's a few rb30/26's around running 11:1, but i can't recall exactly where i read about them (or if they blew up after 6 months)

[JustinP]

Sounds good! I wish I had gone a bit higher on my build (9:1) as I will be using WMI with some safely measures just in case there is a failure of the system.

You could go really crazy and try and implement a DIY direct injection system to assist! Copy the BMW N54/55 design ) Would love to see that one day on an RB.

What are peoples thoughts on building a high comp motor with custom pistons with say 11:1 ratios or around that then running turbo and e85?

[51NNA]

Need more power Simon? Or just building a backup engine, nothing's impossible but you'll need a big budget, personally I wouldn't go higher then 10:1 but if you could pull off 11:1 it would be epic. The tune would have to be perfect and same with the build there's no room for error with that much comp, fuel would need to be under strict monitoring also.

[Simon-S14]

More midrange torque would be great. Don't want to go rb30 due to height. Was going to start building another bottom end and use nitto's new spline drive pump also.

[GTScotT]

Ive found that some of my +T setups have been sensitive to turbo choice. IE with an SR+T I found I could max a T28 on 9.5:1 and smash the performance of the equivilent DET 8.5:1, however moving to a TD05H 18G saw it was a lot harder to get the very most out of it.

In all cases ive experienced the cars have a lot more midrange with the added 1:1

I did however set sail to fail on my 10:1 setup, and am hoping to fix that soon.

[51NNA]

I know this would be abit to extreme for you're application but have you considered a composite turbo setup? ie little turbo blowing into a bigger turbo so there's boost throughout the rev range? Ive had great success with this on duramax's but its been a HUGE budget involved. Considering though you have easy access to custom metal fabricators this wouldn't be such a challenge. Food for thought.

[TiTAN]

thats a compound turbo setup, the S14 engine bay is already smaller than the skyline one and you want to put 2 turbos in it plus the plumbing and multiple wastegates to get a compound setup working?

[GTScotT]

R u sure its smaller man? Im pretty sure the area across the firewall is the same but theres more room between the strut towers (i could be wrong). Its definitely shorter though.

Imagine rocking up to ANY event with a compound turbo setup, LOL

[Simon-S14]

it would be cool to do... however in the interest of keeping it simple to avoid things going wrong going compound doesnt really fit the bill

[51NNA]

Got to love iPhone auto correct haha, I know theres not much room, but if you could pull it off imagine the hype, especially on a drifter.

[Simon-S14]

haha i should give it a crack on a bog stock RB30E

[SS8_Gohan]

so what's the basics of increasing the comp of an engine build?

[GTSBoy]

Shave the head, and/or increase the piston crown height.

/basics.

[Simon-S14]

dont want to be shaving the head that much to increase compression... you'll reduce the cumbustion chamber size.

need custom pistons with a higher crown height.

Would love to build a stroker RB28 with 10.5 - 11:1 CR balanced within a micron of its life to allow it to rev, Nitto spline drive pump to keep it lubricated. would be fairly nuts i would thing

[Shane_954]

Brad Sherriff in tassie is in the process of building a new high comp engine for his r32 circuit car. Its early days still but i reckon that will go close to 600rwkw.

Will be interesting to see how it goes.

[SS8_Gohan]

so say with a 2.8, there's no off the shelf sized pistons you could get to get the desired CR?

do custom pistons command a large premium over 'off the shelf' ones?