High compression RB20DET Build in progress

[rb25det250sx]

ahh..i see thanks for clearing that up.

[TimeAttackTheory]

For now im running stock cams. I plan on upgrading to tomei valve springs, retainers, lifters, and cams later on. But thanks, if youre interested in a set of these rods for your RB check out http://www.proengines.com.au

Since this company is based out of Australia you save money on the exchange rate. The rods were 695 AUD which is only about 500 us dollars.

[TimeAttackTheory]

Yep no problem

[Carl H]

good ol'e pro engines...did a crank collar groupbuy a few years ago thru them.took a bit of time but it was a good product when all was said and done.you'll find that with your setup stock cams will severly hinder power potential...around 6300rpm its gonna fall on its face.

[TimeAttackTheory]

good ol'e pro engines...did a crank collar groupbuy a few years ago thru them.took a bit of time but it was a good product when all was said and done.you'll find that with your setup stock cams will severly hinder power potential...around 6300rpm its gonna fall on its face.

I got the rods from pro engines but I got the crank collar from rhdjapan.com before knowing pro engines sold crank collars at a lower price. Im going to build the head later on unfortunately I have to use the rest of my money to pay for college. If I wasnt in college I would build the head now. Im not sure if they had a group buy in the past.

[TimeAttackTheory]

good ol'e pro engines...did a crank collar groupbuy a few years ago thru them.took a bit of time but it was a good product when all was said and done.you'll find that with your setup stock cams will severly hinder power potential...around 6300rpm its gonna fall on its face.

I just recently got my hands on some funds so now i'm going to Pick up a set of Jun Auto Valve springs and Tomei poncams 256mm duration 8.5mm lift!

[b00stinbmx]

this is awesome. im very interested to see what happens with this when its all said and done. can;t wait to see some #s and hear it run!

[deuce4Oh]

might be one to watch

[Seishuku]

Lookin good!

I love 10:1 and turbo, you really get the best of both worlds.On 93 gas you don't really need det suppression, but tuning is tight. I personally use water+meth injection on my 10:1 SR, but I didn't use aftermarket pistons, they're stock NA ones. So I gotta be nice to them.

[TimeAttackTheory]

Yikes @ stock n/a pistons in a turbo sr...lol yes be nice to them. In the meantime id save up for forged aftermarket pistons if i were u just in case the pistons you have now fail. Im guessing theyre either cast or hypereutectic since its from an n/a car and broken ringlands are no fun.

[boosted98gst]

another option is just like how I have set up on my 05 evo I run e85 and still have a second tune for pump gas just incase I run low and no e85 around.

Another question are the forged rods lighter then the stock oem rods that came out? was wondering this.

[Seishuku]

Yikes @ stock n/a pistons in a turbo sr...lol yes be nice to them. In the meantime id save up for forged aftermarket pistons if i were u just in case the pistons you have now fail. Im guessing theyre either cast or hypereutectic since its from an n/a car and broken ringlands are no fun.

I didn't rebuild it either, I just turbocharged it as it sat on the palette right from JDM!

I did inspect it though, it was pretty clean.

From what I've seen, the ringlands are pretty decent in size, but it's still a cast OEM NA piston, so it's gonna fail some day. Especially with out oil jets cooling it, though the water/alcohol spray does drop the EGT and combustion temps a LOT, so I shouldn't have to worry too much (so long as it doesn't lean out too much).

At least with 10:1 on an RB, it's with aftermarket pistons. So there's lots of ringland beef there!

[TimeAttackTheory]

another option is just like how I have set up on my 05 evo I run e85 and still have a second tune for pump gas just incase I run low and no e85 around.

Another question are the forged rods lighter then the stock oem rods that came out? was wondering this.

Two tunes...thats a good idea. The forged rods are insanely lighter than the stock rods! Its a night and day difference in weight. I didnt put the stock rods on a scale to compare them but you can definently feel the difference in weight in your hand.

[TimeAttackTheory]

I didn't rebuild it either, I just turbocharged it as it sat on the palette right from JDM!

I did inspect it though, it was pretty clean.

From what I've seen, the ringlands are pretty decent in size, but it's still a cast OEM NA piston, so it's gonna fail some day. Especially with out oil jets cooling it, though the water/alcohol spray does drop the EGT and combustion temps a LOT, so I shouldn't have to worry too much (so long as it doesn't lean out too much).

At least with 10:1 on an RB, it's with aftermarket pistons. So there's lots of ringland beef there!

Ohh so you bought a sr20de then boosted it. Gotcha... But why not just buy a sr20det? Was it because you got the swap at a really good deal or something?

I'd be interested in seeing someone swap a sr20de into a 240 then bolt on a sr20ve head and run some crazy high compression like 13.5:1 It would be like the nissan equivalent to an ls/vtec engine. Hmmm this could be an idea for my next build. Ive been contemplating a powerful n/a build for an s13 coupe but ive been leaning more towards a vh45de swap.

[Yellow4g63]

Ohh so you bought a sr20de then boosted it. Gotcha... But why not just buy a sr20det? Was it because you got the swap at a really good deal or something?

I'd be interested in seeing someone swap a sr20de into a 240 then bolt on a sr20ve head and run some crazy high compression like 13.5:1 It would be like the nissan equivalent to an ls/vtec engine. Hmmm this could be an idea for my next build. Ive been contemplating a powerful n/a build for an s13 coupe but ive been leaning more towards a vh45de swap.

13.X comp with a VE head is easy to do Just use SR16VE pistons and you will have it.
Modified by Yellow4g63 at 12:12 PM 9/6/2009

[TimeAttackTheory]

Yeah i've heard that before. But are those pistons cast? I wouldnt want to risk them breaking on me

Check this out. This is an s14 with a neo vvl head





and finally neo vvl with turbo

[Yellow4g63]

Yeah i've heard that before. But are those pistons cast? I wouldnt want to risk them breaking on me

Yeah those are cast, 13.X would have to be made since most off the shelf ones are 9.1 or 12.1.



Stock SR20VE on left and SR16VE on right.

[TimeAttackTheory]

The ring land on the n/a piston looks slightly more beefy than that of the turbo piston. Cp makes custom pistons at a reasonable price. You just tell them what compression ratio/ bores size you want but its better to calaculate the compression ratio yourself since they calculate compression ratio's based on stock parts, stock head gasket thickness, deck height, stroke length, etc.

But 13.x:1 is awfully high for a street car but i'd just track the car on the weekends.

Have you seen this before? It's a B7 Audi RS4. 4.2L V8 12.5:1 compression ratio with a supercharger! 535whp @ 8250rpm

Check it out...http://www.youtube.com/watch?v=FBkX8GS5FoY

[PorkChopExpress]

manufacturers usually have higher compression forced induction engines because the just bolt a supercharger to a stock motor, also probly helps a little bit with the fuel emissions they have to comply with. like they did with that rs4 you just posted. boost always wins in making power over compression and timing especially if your going for pump gas power.

[TimeAttackTheory]

But that's not the case with the RS4 or any Audi. I used to work for Audi and I noticed they re build and change alot of things on their motors. The engine in that rs4 is the same engine from the A6, S4, R8, A8, and Q7 but each one is built differently with different compression ratio's, connecting rods, oil pumps, water pumps, intake manifolds, fuel management systems etc.

For example, Audi a6 engine = same engine as rs4 with different intake manifold, conrods, cams, valve springs, pistons, and ecu, rs4 engine = same engine as r8 with different intake manifold.

The 4.2l RS4 from the factory is n/a. Im not trying to sit here and advertise Audi but if you ever get a chance to see one in person at a dealer you should try to get a test drive lol It's the only car i've ever seen that comes stock with a stand alone fuel management system, coilovers with external resiviors, and 4 fuel pumps... It gets like 8mpg though

[jdmser]

I'm really interested in seeing how your build goes. I made a small error when ordering the pistons for my RB24 from JE. I was copying the numbers I found for the Tomei RB24 and used 52cc for the combustion chamber volume when it's only 42cc stock. I plan on running a custom head gasket for now. A 2mm gasket will put me at 9.7 and a 3mm will put me at 9.0.

[TimeAttackTheory]

Ohh... I would have just measured my combustion chamber volume myself. It's pretty easy. Leave the spark plug in and fully tightened, You get white lithium grease put it between the valves and valve seats and around the combustion chamber youre measuring. The white lithium grease acts as a seal to prevent water from leaking

Get a piece of plexi glass with a hole in it, cover the combustion chamber. Get a pyrex test tube, fill it with water and write down how many cc's of water is in the test tube then pour water through the hole in the plexi glass until the combustion chamber is full then write down how much water you have left in the test tube and subtract the before and after difference and theres your combustion chamber volume.

Do you plan on boosting high and what fuel are you tuning for premium or e85?

[jdmser]

I would have like to done it that way but, at the time I didn't want to tear apart a running motor. What I'd like to do now is have the combustion chamber cnc'd to remove the squish and have the diameter match the bore. That would put me at 8.5 cr with a 1.2mm gasket. I have an E85 station about 10 minutes from me but, I'm not sure I want to go that route just yet. I like to be able to fill up at work since a get a discount on BP 93 octane.

[240z4u]

I would have like to done it that way but, at the time I didn't want to tear apart a running motor. What I'd like to do now is have the combustion chamber cnc'd to remove the squish and have the diameter match the bore. That would put me at 8.5 cr with a 1.2mm gasket. I have an E85 station about 10 minutes from me but, I'm not sure I want to go that route just yet. I like to be able to fill up at work since a get a discount on BP 93 octane.

IMO, run it at higher compression and see what she can do. This is one of the more interesting things I have seen on the RB forums in quite some time honestly.

[TimeAttackTheory]

More pics for you guys...



Stock Vs. Fidanza flywheel



Stock gt25 snail





I went with Tomei Poncams instead ofthe HKS cams since they were on backorder and I went with supertech valve springs, spring seats, and retainers instead of the jun auto since they too were on backorder.

My cam spec sheet is in japanese, looks cool but I can't read it and I need to degree these suckers!

[jdmser]

At one point in time I sat down and translate the spec sheet that came with my procams but, I don't think it had any more info than what was on the Tomei USA site.

[MasterOfAngle]

Ahh good idea tomei usa site. I should have thought about that.
Modified by MasterOfAngle at 8:06 AM 9/20/2009

[TimeAttackTheory]

More pics of the build up...



















Longblock is now ready to go. Next its time for bolting on acessories and wiring.

[Carl H]

look for my write up on how to degree the cams, there should be links for the cam specs in there.

[Coolwhip]

look for my write up on how to degree the cams, there should be links for the cam specs in there.

zerothread?id=425466

Love the build by the way