Cast EFR 8374 IWG Large StreetPort FC3S Dyno 503rwhp @ 17.5psi
 

Adaptronic S4 PNP ECU
Flex Fuel ; E77
Large Pineapple StreetPort
3" exhaust with RB catback( no cat)
2.5" water to air intercooler system we built
ID1300/ID1700
Stock coils
503rwhp/355rwtq @ 17.5psi peak pressure.

SAE is 496rwhp FYI and it was 98 deg F in the dyno room today...

Very nice! What were IATs at the end up the run? I should have my W2A 9180 on the rollers within a couple weeks. I'm seeing 4F temp rise on a 3rd gear street pull with 85F ambient

Wow that rips. Very nice torque curve. Done right.

Is this motor studded?

Way to go, Elliot. Never a disappointment whenever I open one of your threads.

Actually a mild street port. And no, the engine was not studded... :(

Fixed and ready to go back in...and handle 500 whp...

did it blow?

cracked rear iron

has pineapple solid dowels now and an infini rear iron

Did it knock? or just because of torque?

No knock, and nothing wrong internally. It was not an agressive tune either, not even close. I am starting to wonder if tranny movement is also apart of this problem on the 2nd gens.

I had this once when I had fuel pressure drop. it said pingping and cracked at same place at oil filter pedestral.

there are people running 30 psi and more on non studded engine on pump and water inj. so it makes me believe knock, or abnormal combustion (as in too much chamber pressure too early in the cycle) should must be the main effect, an not engine torque.

I heared some theories one could also cut the ribs in the rotor housing nearest to the dowel location. this should prevent the pressure wave during pre iginition not be able to be transferred to the dowel boss. the rotor housing liner will bend somewhat but this is said not be a problem as its flexible.

I didnt try above technique myself yet.

Yeah this was not meant as any kind of reflection on the tune/fuel/turbo system at all. When i had the block built 10 years ago it was not built for that kind of power it had the early 2nd gen rear plate.

It was due for a refresh anyway. I got 10 years of hard track and street use out of it then decided to push it. I figured better to get it set up and mostly tuned before the refresh in case something happens. It's good to go now...

Turblown/Turbosource did a great job with it. Other than the IWG on the EFR turbos being SOMETIMES susceptible to boost creep everything worked perfectly. Tune was great, car pulls like a mule.

When you say running that setup at that much boost pressure you are probably talking about an FD motor, no a small dowel S4 T2 engine.

I have cracked these irons before, and literally just put the big S5 rear on with our 10mm stud kit and without changing anything it did not happen again. I also cracked my personal S4 iron at 33psi on the 9180, and nothing was wrong inside. This was on OEM 3 piece apex seals too. I also know what the housings, and rotors etc look like when they move around or knock each other etc.

I plan on getting to the bottom of it once and for all on my S4 block( I am putting an S4 rear iron back on, and will just use our stud kit and a tranny brace).

I have a S4 turbo block kicking about the garage. Eventually I plan on putting the EFR on it, but what exactly do you mean by tranny brace? I would prefer to not buy a rear iron if I do not have to. i'm also planning on staying below 400hp

Guessing it installs to the passenger strut tower and firewall on one side and iron on the other?

Thanks for sharing, Eliott. Have you installed one on a customer car before, or would your car be the first?

I'm worried about vibration with something like that... My TII is a part time street car and i hate NVH for street cruising. I had to ditch the banzai engine and trans mounts to get rid of the NVH that kept rattling dash parts to dust...

I had a straight torque brace from the alternator bracket to the strut tower bar as well as Mazda comp engine/trans/rear mounts.

It always bent/cracked my center iron where the passenger side motor mount bolts on.

https://cimg2.ibsrv.net/gimg/www.rx7...87a6e1e1e8.jpg

It would still occasionally break the rear iron at the upper dowel with detonation (damage present elsewhere in engine).

I removed the torque brace on my last engine to save the center iron and it broke the front iron at the upper dowel.

No damage/wear inside the engine- looked good to go.

FD has the right idea mounting the engine by the rear plate so the drivetrain torque can't unduly twist the loosely held together engine stack anymore than just transferring torque to the e-shaft already does.

https://www.rx7club.com/2nd-generati...-holes-986102/


https://cimg2.ibsrv.net/gimg/www.rx7...2eeb1c86ff.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...1a243b5875.jpg

My car will be the first.

I know how to 100% prevent crack plates on FD engines, just not positive yet on the weak dowel S4 motors..

If you can find a viable answer, I'm all ears. I did originally plan on getting an REW for my project, but I now have an abundance of S4 engines I picked up for almost free, so I want to use what I have first.

Are you guys spraying any water when you crack these plates?

Negative. But using somewhere between E50 and E85 fuel.

As Elliot said it was not detonation or knock. Just the engine making more power (bigger bang) than what the plate can handle.

500 RWHP is really quite a bit on a small engine. If you assume a 13B flows about the same air as a 2.6L piston engine, then a 13B is making the equivalent to a 1200RWHP LS1 as far as displacement/power ratios are concerned.

Are you guys spraying any water when you crack these plates?
Just 110 leaded gas for me.

In the past yes, I broke a S4 t2 plate at 450rwhp 10 years ago on stock dowels/tension bolts with 2 stages of 50/50 water alcohol.

Literally slapped a new S5 big dowel rear pate on and our 10mm stud kit and it did not happen again...

I haven't done any testing with E85 so I have no real-world detonation limits to share.
Each power event is different as you accelerate to 8000 rpm it only takes a few to set up preignition and detonation.
My thought is to always use water in the mix to delay detonation.


This is my 8374 on the ragged edge. Boost is 18 psi with the correct amount of advance for 93 oct.

But the pressure is going to high (1430 psi). I feel that the Water/meth stabilizes the burn rate and allows this engine to live at these pressures (and higher).

I also endorse the 3rd gen plates.

Very nice, I have always wanted to set-up and log combustion pressure!

Nice! the other pressure trace, I guess is compression without combustion? 1400 psi is somewhere what low-mid spec turbo piston engine run these days.

What Ign angle you have at this cycle?, to get an rough idea of ignition delay.

Would you say in this condition that you are knock limited, or maximum chamber pressure limited?

Rub,
My guess is max chamber pressure. But I am a big chicken when it comes to blowing up engines.
On the earlier attachment did you notice the pulsing after peak pressure ... that is getting close to a detonation profile I think.

Possible, to get a feel what it looks like I would run the motor into knock at part load, where it shouldnt cause immediate damage. to get a feel about the frequency of the oscialltion.

At work we use knock amplitude or knock peak to peak. this get calculated for as the difference between the unfiltered pressure trace and the pressure trace filtered over the average of the last x measurements (usually around 20 measurements with 0.1 deg resolution, varying with rpm). as a calibration guideline we use rpm/1000 for knock peak to peak signal in bar.

In the first pic of you previous post, do you have any idea why the chamrber pressure lies below the compression trace near TDC? do you think the apex is lifting? What funny is that on these old skool paper comrpession tester you can see where the seal passes the leading plug hole.

"In the first pic of you previous post, do you have any idea why the chamber pressure lies below the compression trace near TDC?"
One is theoretical and the other is actual collected pressure data.

Great questions .. but let me apologize for taking this rabbit track away from Turblown's thread.

I should find some time to make a separate compression testing thread.
Barry

"I should find some time to make a separate compression testing thread.
Barry"

:nod:

https://cimg6.ibsrv.net/gimg/www.rx7...07236128d3.png2nd try to upload the picture
Car is back togeather finally, scope creep ended up including a paint job....BMW sakhir orange metallic...will get it back on the dyno in the spring, it's now down for it's long winter's nap...

Not to be "that guy", but the pic isn't loading for me.

I think we all "that guy"