compression ratio vs boost psi

[s2kadl]

Yes, there is no way I could run 15psi on stock compression without the cooling and octane properties of E85, well safely anyway.

[Weq]

[with respect to building engines]

WIth high compression, all it takes is a bad batch of fuel for a new motor to be had.

On the street, if u want power on pump fuel, low compression is the way to go. Low compression is forgiving. And in the real world, if u daily drive ur beast, this is the difference between life and death (of ur motor).

E85 isnt pump fuel here, yet...

[s2kadl]

From memory some of the LS1 LS2 turbo guys in NSW are running E85, I reckon there are 4 or 5 servos that carry E85 over in NSW. From memory some Enhance petroleum and United petrolroleum.

[Weq]

From memory some of the LS1 LS2 turbo guys in NSW are running E85, I reckon there are 4 or 5 servos that carry E85 over in NSW. From memory some Enhance petroleum and United petrolroleum.

Like i said, it isnt exactly pump fuel. Unless your a weekend warrior that doesnt venture 200kms (E85 runs at 9:1 stoich, double the fuel) from there home, then its not viable yet.

I just did 2400km round trip with my Z, boosting hard after 10hrs running, stopping off at remote servo's for fillups. Unless you can do that, you might as well be running C16.

[s2kadl]

You are right, its definitely not an option for those who daily drive high kms. My S is just a weekend car and so far Im using about 30% more fuel compared to when I was at 12psi on ULT98. C16 was an option but costing 6-7 times that of E85($1.22/L) made it unviable for me. The extra 3 psi on E85 netted me an additional 38 rwkw.

[IEVAQ8]

I don’t understand how some of u people with no experience can comment about a high compression boosted Honda on pump fuel is no good for a daily driver………

Please give me some reasons or experience to back your negativity…………on high comp with low boost on a big turbo……

as my daily dc2r with stock compression (11.1) and gt30 on 7.5psi is making a healthy 239.8kw and hasn’t missed a beat yet (almost a year)………it gets driven every day and on the weekends (rain, hail, shine, 45degrees or 10degrees), also goes to the drag strip when I can……………..
anything regarding boost/higher compression is all in the tune and the quality of the parts u decide to use……………

[votek]

the tune is everything... what variables you have. its all about the tune!!!

[Limbo]

i agree i drive mine all the time without fail no probs at all

I don’t understand how some of u people with no experience can comment about a high compression boosted Honda on pump fuel is no good for a daily driver………

Please give me some reasons or experience to back your negativity…………on high comp with low boost on a big turbo……

as my daily dc2r with stock compression (11.1) and gt30 on 7.5psi is making a healthy 239.8kw and hasn’t missed a beat yet (almost a year)………it gets driven every day and on the weekends (rain, hail, shine, 45degrees or 10degrees), also goes to the drag strip when I can……………..
anything regarding boost/higher compression is all in the tune and the quality of the parts u decide to use……………

[nd55]

There's a David Vizard article floating around the net which lists rough power differences across a range of CR's for a NA motor. .

I think it was in the range of 10-15% improvement for a 8-12:1 CR range.

This using pushrod V8's.

... and this link comparing 9:1 & 10:1 from elsewhere on this site:

http://www.evans-tuning.com/dynocomp_9vs10to1.html
Nick.

[votek]

Yes, there is no way I could run 15psi on stock compression without the cooling and octane properties of E85, well safely anyway.

anyone ever run 15psi on a stock bseries motor? rod gone?

[DLO01]

Yes its been done before. Think it was a B16A2. No problems. Depends how you drive it. On the street, on/off boost, no problems.

[Sexc86]

I Did look into High compression + boost with an engine builder a while back. They basically said there is a Happy/medium level to be found betweeen timing and CR. Higher compression = less timing (assumeing useing pump fuel). Timing is what makes you power.