High Compression and whipple on e85

[caaron101]

Hey guys I'm building a new motor, I think I'm going with a teksid block, I have a gen 1 2.3 whipple, stage 3 comp cams, 1 7/8 headers and full 3 in exhaust. I'm going to be on straight e85 all the time, I'm going to see what numbers the 2.3 makes but will eventually move up to the 2.9. I want to up my compression to about 10.1, with that much compression can I run more than say 22 lbs of boost on the 2.9 when I get it? Because I know that's around there sweet spot. If not what compression should I go with then?

 

[gabe1530]

Yes you can run that much compression. There are a couple guys that are running 11:1 with that much boost.

 

[ugotbit03]

Search 03Steve's posts. He's a high compression Whipple pimp!

 

[98 Saleen Cobra]

My buddies 460X short block from ford racing is 9:8 and a stroker with stock heads, stock cams, ARH 17/8'' exhaust and a whipple 2.9 at 22psi (3.0" pulley) and E85 made 800rwhp SAE.. None crusher..

Run higher compression

 

[Tractionless1]

From what I've read E85 loves flat topped pistons. Build your motor accordingly then taylor the boost to the build. Worst thing that can happen is running low psi which = colder boost charge.

 

[caaron101]

But dosent lower boost on a 2.9 make it inefficient? Or will the higher compression make up for that? With everything I have and with the 2.9 I would like to get 800 to the wheels. Or should I run less compression and up the boost to make the 2.9 more efficient to make the power I want?

 

[Jcobra03]

my car is a 11:1 with 25 lbs vmp tvs

 

[caaron101]

Dang! That's exactly what I wanted to hear! How much power did you make through the auto?

 

[Jcobra03]

dunno. i havent dynoed it since going auto . you can do the math though 3680lb going 9.40 @ 144 mph

 

[FoMoCo08]

Tractionless1, Care to elaborate ?

 

[98 Saleen Cobra]

It's pretty simple. The harder the RPM you spin on the blower the more heat you create for IAT's.. The higher compression can achieve the same if not more power on a lower boost since the engine makes for more without the s/c naturally aspirated..

Example

10:1 compression engine with a 2.9L whipple @ 15psi on E85 makes 700rwhp..
8:5 compression engine with a 2.9L whipple @ 20 psi on E85 makes 700rwhp..

You're spinning the blower harder with more boost there for creating more heat..

 

[FoMoCo08]

I'm inquiring about his statement "E85 loves flat top pistons" I don't need a lesson on cylinder pressure. I assure you I understand the internal combustion engine quite well. A flat top, effective dome, or dish aren't a determination of the type of fuel used. Cylinder pressure is the determination of what fuel is to be used. That being said an effective dome may have an impact because it inhibits flame travel (not a good thing) but that is irrelevant to this topic. What I would like to know is how E85 loves a flat top piston. E85 loves higher compression, higher cylinder pressure ? Yes. But the way you achieve that compression ratio/higher cylinder pressure from a dish to a flat top has nothing to do with it to my knowledge. Now if someone would like to explain to me the properties of E85 that make a flat top piston more effective (other than the raise in compression from a dome) then I am all ears. Thanks

 

[98 Saleen Cobra]

Well you didn't specify what you needed clarification on.. E85 loves higher compression.. I remember reading a article that closer to you get to 14:1 compression the fuel burns better or something.. I don't know the truth to that nor can I remember reading it.. My buddy read the same article maybe he'll know.

I didn't mean to insult you knowledge base on combustion engines lol. I thought you were talking about the cooler boost range.

 

[FoMoCo08]

Haha, it's all good. I was just inquiring about his statement. Not trying to question what he said, I was hoping he could elaborate on it. More than likely what he's seen is X motor made XXX power with dome pistons, and then XXX power with flat tops. And the gain was just from the increase compression.

 

[98 Saleen Cobra]

Oh yea I see what you're saying.. I mean like you said anything with more compression is going to make more power. I don't think I've seen a domed piston + boost setup yet though.

 

[ugotbit03]

When we talk about blower efficiency, we should be talking in blower RPM not boost.

From what I've read/been told the 2.9's peak efficiency is around 18,000 RPM.

 

[FoMoCo08]

Domes are pretty much the last way you want to make compression. They are terrible for flame propigation. But at the same time an engine with a dome piston at 11:1 vs an identical engine with 10:1 and a dish or flat top. The 11:1 engine is going to make more power. But if there is any way possible in that application to raise the compression without using a dome, do that. If that makes any sense.

 

[gabe1530]

i believe the efficiency rating of e85 is at its peak around 13.5:1 compression. im not totally sure on this as i read it on here and cant find a source to cite it correctly. it might have been in an article posted in the distillery by 03sleeper.