I am running an Rtek 2.1 with stock turbo and recently my engine died. I highly suspect that the aggressive stock timing maps (really my lazyness, since I had a printout of Arghx's boost based timing maps in the car at the time but I digress...)

I was pulling out of a toll both/onramp that merges into a single lane before entering the expressway. I'm doing maybe 15-20. I look in my rearview and see this SUV fly through the sunpass lane with no apparent intent to slow down. So I redline 1st and 2nd and go WOT in 3rd until 70-75 at which point I shift into 4th and let off the the throttle. Right about this time I look in my rearview and see a car fast approaching ( in the slow lane mind you) so I floor it in 4th and I get to maybe 4-5k and I feel a slight shudder, then I'm slowing down....... No loud pop, no metalic ping, no audible popping just and little shake and done.

I roll to a stop and tried to restart - no dice. A normal engine turns over @ a couple hundred rpm and has compression bumps. Mine sounded like an empty blender and was turning over at prolly 1k or more. Street Diagnosis: No compression.

I was running about 14 psi on the stock turbo, AFR was mid 11's to low 12's on 87 octane. I have a V mount IC and ambient temps were roughly 70*.

I'd been running this setup for the past year, but I guess a 147k stock motor has to go at some point...

 

heh, sorry to hear it bro.

but at 147k... you may have just worn down the seals and grooves until one of them rolled out.
it's good tho, you made that motor last a long time.. at 140k miles the housings would need to be replaced anyways.

i will say that the stock timing(even with the rtek boost-based timing retard feature) wasn't made for 14 psi. neither was the stock turbo.

on a lighter note, my 9.7 cr rotors and 87 octane is holding nicely... Arghx's boost based timing, are a really good start, i've only taken the timing back here and there. have yet to add any tho, i wonder what power lurks...

 

Sharingan sorry for your loss.

You're getting by on his timing maps with 87 octane and high cr rotors? Awesome cause I was thinking a high cr tii would be fun.

 

getting by, that makes me laugh.. i've gotten knock in 3rd, and had to data log and find the "spot" and retarded that area, but his maps are a really good starting point.

Even on the stock turbo and top mount, and no more then 5 psi(yay no more boost creep) it's quite fun, i can hit 5 psi by 2400rpm. waiting on a new mbc to crank it up... but then again, i have FD twins that are almost ready to be put on the fc block, expect a thread for it.

 

Exactly.

I found an s4 n/a block w/ 15k on a rebuild, so I'll be doing a quick and dirty 6 port turbo setup and I will be inputting those timing maps before the first startup!

I really wanted to find an S5 n/a but they all had at least 100k, and I would have needed the s5 counterweight which I don't have time to acquire. Well I guess that still means I have something to look forward to on the 4 port block I'm putting together. And I've got a line in on two S5 rotating assemblies for the cheap

 

i've got 4 s/5 na assemblys, one for the 10thAE (FDtwins soon!) one for the 91 vert(being streetported mated to an RX-8 6SPEED), one for the 85 GSL-SE. and one set still wrapped up from cleaning. what can i say, i love high comp.

 

You guys are brave, I don't use 87 in anything I own('course everthing I own is modified). Personally I would not want to see 12.0+ AFR's with 12-14 lbs of boost.

 

Too bad about the motor & good luck with the new one.

Wonder if/how long it would have lasted with 'safer' timing?

 

If its safe enough for factory, it couldn't be that dangerous. It's simply a matter of tuning. I honestly stopped looking at the gauge after about 10 psi, so I didn't have to "see it" per say

I have every confidence this engine would have ran the turbo into the ground and kept chugging along at an unimpressive 90-92-91 / 87-86-86 until I finished my other engine.

 

Sorry to hear it.

87 octane is the factory recommended fuel grade because the TIIs only run 6 or 8 psi stock. With all the extra heat that comes from 14 psi (turbo wellllll outside its efficiency range), you really shouldn't risk it. I haven't used anything other than 91 since I had a bone stock TII.

As for timing, I backed it off 1-2 degrees in the mid-range and as much as ~5 up top. The stock maps use something like 34 degrees of timing at 100% load and 7k RPM!

 

Actually, I do use 87 in my '81, but, since I'm not keeping it I don't count it as mine.

 

Got the old engine out today....All 6 apex seals are busted so it must have been some supreme detonation. I also must have happened very quickly because all I felt was a slight shudder for less than a second.

I'm just going to be running the stock turbo until I get my hybrid built I would prefer to not throw chopped up overheated air at a high comp engine.

Your 81' is turbo?

 

Would you kind enough to share your setup?

 

14 psi on the stock turbo was your problem. That is way too much boost for a stocker. Your turbo was prolly putting air out in excess of 500 deg F.

 

14 psi is certainly not on the efficiency island of the stock turbo, but 500* seems a bit high, none of my previous data logs showed temps above 200* which means my IC would have to be removing 300+.....which I doubt.

 

Update: The S4 n/a engine I bought was apparently put together by monkeys. As I was installing the flywheel and clutch I brushed against one of the tension bolts....it spun :shocked:. So I decided to check the torque on all of them. To my surprise only 4 bolts were torqued to factory specs 25-30 ft/lbs. So using the factory diagram I retightened the loose bolts.

Apparently the engine didn't like this as it proceeded to weep coolant between the housings and irons at 4 different locations upon start up as well as show signs of flooding. I tried to use the block seal trick and it did not work, so I was forced to pull the engine again for a rebuild.

I already had a set of S5 turbo irons so I have decided to just use the n/a rotating assembly in a turbo engine as opposed to the 6 port irons. This should provide even better low end/response than the 6p-t which is desirable since this will be a daily / auto-x car.

 

I've run 14psi peak boost on a stock turbo with stock ECU + SAFC + FMIC and 93 octane fuel. I'm not saying I recommend it, but it's not necessarily going to result in instant engine death.

^ Even if there were build mistakes, It's not surprising that ~25 year old tension bolts on similarly old housing won't hold torque too well. If you think about it, most of the time when you pull the head on a piston engine you use new tension bolts.

 

14psi on 93 may not be a death scentance but 14 psi on 87 w/ stock timing maps can only last so long...and I guess I figured out how long that is. I think the only reason it took this long to blow is because i never did any long 4th or 5th gear pulls.

There's "not holding torque properly and then theres "the bolts spin when you bush your gloved hand against them" I'd trust 20+ year old bolts before I trust whoever put that engine together.

I just got back from the shop today and the genious didn't remove the n/a exhaust sleeves from the housings like I requested. So instead of assembling the long block I had to spend the afternoon carefully chisling and grinding the n/a exhaust wings out. Kinda sucks that the material is not magnetic, but I stuffed and entire shop rag in the housing and I'll hit it w/ a shop vac after I'm finished.





making progress, but obviously not finished