My low cost high compression daily driver E85

[turbo addict]

This thread has inspired me to run my 2.4 in my n/t car. I've been doing so much research and then just came back and measured my piston dishes for my 2.4 4g64. It is 15cc DISH. Swapping a 1g or 2g 47cc head onto this block will not alter the compression that the motor originally had from the factory: 9.5:1 (per the 2.4L FSM).

The DOHC 2.4 motor has a head identical to the 2g head. Head volume and all.

Here is a pic of the 4g64 DOHC piston beside an n/a 4g63 piston:

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Look how healthy that 4g64 "SA" dish is. No need to worry about valve to piston contact since the n/a 4g63 piston has so much less dish. The valve reliefs of the n/a 4g63 piston are much shallower than the dish of the 4g64 "SA" piston.

So again to verify. IF you have a 9.5:1 CR (from the factory) 4g64 that had the DOHC head, then you can swap dsm heads all day long and your CR will be 9.5:1 not +11:1.

Here's a CR calculator for reference.

Do you have a galant gs head? I have a friend that had one and the machine sop said that the cc was 43cc or so. But smaller than the regular dsm heads.

 

[JayRolla]

I would like to add that Kevin at Jacks shop went to a junk yard and pulled a 2.4L out of a Mitsubishi Expo and through a 2.0L head on it. Car had over 220psi on compression tests. He built the car in two days and hit the strip. Ran a low 11 in our altitude. One of the pistons did give away after a while but he was making some good power.

 

[mobythevan]

Yeah, I talked to Jack about that build before I started this one, that is what I was mentioning in the first thread that the local guy had already built this combo and claimed like 11:1 compression(it is actually closer to 12:1 with a single head gasket). BTW, I got my HKS 272 cams.

 

[habitatguy187]

Updates?

 

[mobythevan]

My friend is building a new engine right now and I am helping him. After that I should get time to rebuild mine with the new pistons and cams. I need to order pistons and injectors.

 

[turbotalon1g]

^sweet.

Good news is I have a new dsm that probably needs a new motor and I plan on doing this to it.

 

[Andrew7DG]

Very interesting build

Bringing this back from the dead a little.

I am now curious also of this build. My altitude is lower then where you are running but I want to see if it will still hold together.

Found an engine at the U pull lot and we have plenty of E85 stations around here.
Using megasquirt for a standalone system also so it should be pretty similar.

I also have a set of 272s sitting around.

If she blows up, well move onto the next engine. If the crank is still good after it blows up, I have a 4g64 block that need a new crank.

The question is what turbo to run? go for a small 14b? 16G? 20G?
It isn't going to run much boost, and it is going to spool quickly and it isn't going to run high PSI either...

 

[dsm-onster]

14b with an ebay 16g turbine housing and a holset adjustable actuator . . .

 

[mobythevan]

I have not installed my 272 cams yet. I am liking the low end grunt with the stock cams and high compression so much that I am afraid to change cams. This car gets off the line so quick and in the boost so early that it is tons of fun on the street. I am just enjoying driving it for now, I am always bouncing between keeping this setup or going to the bigger cams and lower compression. Right now I like it the way it is for the street.

 

[dsm-onster]

I smell manual tranny failure in your future . . . But, an auto setup with even the stock stall looks very nice with what's going on, in my opinion.

 

[mobythevan]

I am noticing that the rear has a lot of slack in it these days. I use to have a four bolt rear waiting to swap in, but I sold it. Hope this one holds on for a while. Automatic would be really fun in this car, maybe I will look that direction. I hadn't really been thinking about it but you bring up a good point.

BTW, for the guy asking about timing up top it is 18 degrees total at 180kpa.

 

[jwahl16]

Wow i just saw this and am impressed. I was wondering if anyone knew what the CR would be if you had used a 4g64 block from a Spyder GS? And how much boost could a 12:1 CR handle? As of now you have 14 psi on stock pistons, but if you were to upgrade to wiesecos witht the same CR, could you throw 20+ psi at it?

 

[dsm-onster]

From my experience, you could apply more boost to even this setup as is. Ethanol doesn't knock much even if you try. But also from my experience, n/t pistons like ZERO knock. So the wisecos can take a string of knock and move on unimpaired. But the ringland spacing for these and 4g63 n/t pistons would crack to hell. The question isn't durability at boost or even power. It is whether a relatively minor knock event will put you on the side of the road.

E85 is wonderful stuff.

 

[jwahl16]

Ok, so it's safe to say 4g63T pistons are more durable than the g4cs sohc pistons correct? If he were to use upgraded, or even stock 6 bolt 4g63T pistons, would it maintain the CR with the increased "knockability?"

And yes, e85 is great, i can't wait to switch (that is if they ever start to sell it around here...)

 

[mobythevan]

Most of this has been hashed over earlier in the thread, but 4g63 pistons do not yield nearly the compression because of their dish. You can look back through the different pictures in this thread to see what I mean. I would love to have high compression wiseco or magnus pistons, but I'm a relatively low budget guy.

 

[Jankenshank]

so what became of this mythical beast?

 

[mobythevan]

I am still driving it, but only about once a week. It is still the same configuration. In the meantime we installed MS2 on my friends talon. Right now I am working on my V8 rx7. I have an MS3 to put on it so I am playing with that. My Talon needs a paint job really bad, otherwise I just drive it and have fun once in a while.

 

[Jankenshank]

so its still performing as last described?

have you touched the boost?

did you ever dyno it?

 

[mobythevan]

That's it. Still running the same boost and performance. I went to farrier school and have been working with horses a lot this last year so it has never made it to a dyno yet. I will have to dyno my rx7 so maybe when I get to that I will also be able to dyno this car. I know jacks transmission does free dyno days sometimes. Maybe I can hit one of those.

 

[turbotalon1g]

V8RX7 is my dream car, can't wait to start mine.

 

[Jankenshank]

Im thrilled that this is still going! i am really excited about my build now, if only i could find stock forged 4G64 pistons. know of any?

BTW what did the piston to valve clearances end up being?

and i have a shot head that i have lying around and like the look of yours! just need to find a band saw strong/big enough.

cheers janken.

 

[mobythevan]

The only pistons that will give this high of compression are the SOHC pistons from the G4CS. I think we talked over earlier (I did not look back in the thread) that the 4G64 pistons do not have the same dome to them.

I can't remember now what the clearance was, but one tooth off on cam timing makes the valves hit.

Good Luck. This engine is fun for a ~300hp. I will likely end up putting lower compression pistons at some point and turning up boost. When I have money again??

 

[Jankenshank]

just to confirm, you had a 8V head and you just swapped the DOHC onto it without any clearance issues?

 

[mobythevan]

Right. 4G63 head on 8valve engine. The pistons are clearance for sohc head. The valves don't have much clearance because the valve reliefs are not in the correct position with the 4G63 head.

 

[Jankenshank]

i picked up a g4cs tonight and will be doing roughly the same as you thanks for the inspiration!

if you would like to follow i have created a build thread on a local forum
Janken's Hybrid High Compression Boosted Engine Build - TennSpeed

thanks! and i will probably will be asking you more questions in the future.