Try to build turbo e36 m50b30 with bad fuel 87 octane.

[dovlet]

Hi Gents,

As i said we have superbad gasoline 87 octane. I want to decrease CR to 9:1 or even less with double head gaskets. Perhaps will replace also piston for 2jz. Csracing Turbo kit is planned to be use. Target point is 400rwhp with some plug and play stand alone ecu.

Waiting for you advise & recomendations.

[rajicase]

My advice would be don't do it. Can you get methanol? Anything to raise your octane?

[tptrsn]

Does anyone know of a combination of crank/rods/pistons that will give him some really low compression even if it doesn't use the long stroke crank? It seems from what he has told us in the E39 forum that the best he can do is plain water injection in combination with his shit gasoline.

Dov, if you don't find anything else, I think someguy2800's build thread might provide detailed measurements for a lot of rods and pistons that you might find helpful for your achieving your low compression objective. Although I've never really looked at things that way, so I don't know for sure.

[dovlet]

Does anyone know of a combination of crank/rods/pistons that will give him some really low compression even if it doesn't use the long stroke crank? It seems from what he has told us in the E39 forum that the best he can do is plain water injection in combination with his shit gasoline.

Dov, if you don't find anything else, I think someguy2800's build thread might provide detailed measurements for a lot of rods and pistons that you might find helpful for your achieving your low compression objective. Although I've never really looked at things that way, so I don't know for sure.

Tq bro, will try to find that thread.

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My advice would be don't do it. Can you get methanol? Anything to raise your octane?

I have no choise. The maximum i have is water or vodka injection.

[Vug1]

I've seen few projects with 318is pistons used due to lower compression height. AFAIK they are 85mm

[JOMARO]

you can use M20b20 or m20b27 130mm rods and what ever piston you d like , not the best rod/stroke ratio but it works

[hsvturbo]

One combination would be to run M54 pistons with a 84mm crank from a M52 and 135mm rods. The piston would be approx .184" below the deck at TDC killing performance, but result in a ~7.75:1 CR.

using an S50b30 85.8mm crank instead would result in a ~8.44:1 CR.

the above resultant data is using a 210mm block deck height.

as mentioned before, finding a meth station might be a better option.

[Butters Stoch]

Didn't MERT play with this years ago ? He was the best. I think he even got down to 6.xx:1 iirc. All cause he wanted to run 50 psi or some crap.

I would get a huge turbo with a small back housing and keep it to 10 psi.

Sent from my E6782 using Tapatalk

[tptrsn]

Pondering the vodka injection a bit more, it seems kind of perfect as long as you can get vodka cheap enough. Assuming your vodka is similar to what we have over here, it is 40% ethanol, 60% water... Pretty excellent for injecting into an engine to combat detonation, and then celebrating with after the event, haha..

[hsvturbo]

A 75mm stroke, M52B28 pistons on 135mm rods would be ~6.5:1 CR.

75mm stroke, M54B30 pistons on 135mm rods ~5.4:1 CR.

drilling a 1/4" diameter hole thru the existing pistons might be the best, cheapest and easiest to prevent detonation at any boost level on 87 octane. I'm sure the OEM CCV system will work just fine .

[dovlet]

you can use M20b20 or m20b27 130mm rods and what ever piston you d like , not the best rod/stroke ratio but it works

What that gives me? Is that decreasing my CR?

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I've seen few projects with 318is pistons used due to lower compression height. AFAIK they are 85mm

What will be mine cr then?

[dovlet]

One combination would be to run M54 pistons with a 84mm crank from a M52 and 135mm rods. The piston would be approx .184" below the deck at TDC killing performance, but result in a ~7.75:1 CR.

using an S50b30 85.8mm crank instead would result in a ~8.44:1 CR.

the above resultant data is using a 210mm block deck height.

as mentioned before, finding a meth station might be a better option.

This is interesting. I can find any thing from m50, 52, 54 or 40. We have no here s series engines. Will be playing with m series.

[JOMARO]

[QUOTE=dovlet;29920554]What that gives me? Is that decreasing my CR?

yes
with the 89.6 crank+130 rods + m52 or m50 vanos pistons
As I remember you ll be in the 7-8 cr ratio

[someguy2800]

I haven't done the complete math but I did some rough calculations on my phone and an m52b28 crankshaft and rods with m54b30 pistons and stock m52 head gasket would be around 8.5 compression. Combine that with water alcohol injection (vodka would be perfect) and I think you will be just fine.

[jakermac]

A 75mm stroke, M52B28 pistons on 135mm rods would be ~6.5:1 CR.

75mm stroke, M54B30 pistons on 135mm rods ~5.4:1 CR.

Where do you think those numbers would end up with the 140mm rods from the M50B25tu?

[hsvturbo]

Where do you think those numbers would end up with the 140mm rods from the M50B25tu?

With the 140mm rods, the CR would be ~9.7:1 with the m52 pistons with the 75mm stroke. This combination would position the Piston about 0.030" below the deck, which is better then a stock M52B28 at TDC.

140mm rods, 75mm stroke withe the M54 pistons would be ~7.2:1 CR.

anywho, if anyone wants a copy of the spreadsheet I have to calculate this, PM me with your email address and I would be happy to send it to you.

[dovlet]

Currently i am running m50b20 block with pistons rods and crank from m54b30. Head gasket is 1.74mm. What is mine CR?

Also, what does XXmm stroke means?

[someguy2800]

Currently i am running m50b20 block with pistons rods and crank from m54b30. Head gasket is 1.74mm. What is mine CR?

It would be the same as a stock M54 which BMW says is 10.2

Also, what does XXmm stroke means?

The distance the piston moves up and down.

[dovlet]

It would be the same as a stock M54 which BMW says is 10.2



The distance the piston moves up and down.

But mine head gasket is 1.74mm

[hsvturbo]

But mine head gasket is 1.74mm

1.75 mm is the stock thickness, so ~10.2:1CR is correct.

[dovlet]

1.75 mm is the stock thickness, so ~10.2:1cr is correct.

tqvm

[someguy2800]

But mine head gasket is 1.74mm

M54 has a thinner head gasket but the deck height of the block is also taller so it works out to be the same.

[euro2fast4u]

I think you guys are over thinking this.

difference between 87 and anything is the amount of timing you can add.

91 octane you may be able to have 12 degrees at a certain rpm and load
87 you may have 8 degrees.

Yes you are not going to have as much torque at this point but he still may be able to make his goal with stock compression ratio. Instead of wasting months of time and $$$. Build it, get a good freaking tune and enjoy.

Otherwise just distill e85 and add all the timing.

[someguy2800]

That is not true at all. All fuels have an auto-ignition temperature. Once you reach a certain point with boost, compression, and intake temperatures there is no amount of timing retard that will keep it from auto-igniting and detonating its brains out. Its not as simple as just taking timing out.

[tptrsn]

Related to that, another interesting thing I recently learned is that E85 actually prefers LESS timing than gasoline in conditions where the gasoline would not be knock limited. I.e. if the conditions allow for tuning each fuel to MBT, then gasoline wants more advance than E85 does. Obviously most of the time pump gasoline will have to have less timing than either fuel wants for MBT because it will be knock limited.

But for sure it absolutely is not as simple as just taking timing out.