Will STi7/8 engine accept 1.4 bar up to the redline
 

I guess a good subject to be discussed :
Assuming correct mapping, no det, "in the range" EGT, will a STi7/8 engine accept 1.4 bar (or more) up to the red-line (or let's say up to 6500RPM) with long term good reliability.
This assumption corresponds to about 390bhp. We all know the STi's engine can be reliable at 350 bHp, but what about such a power, boost pressure ?

Are you talking about the JDM or UK STi?
I think Bob Rawle is the best person to talk to if you are desperate for this sort of power ;) but Bob has an MY03 JDM car which has a stronger engine than its euro counterpart (plus different turbo etc).

Tony:D

Xavier is already running this sort of power Tony with a 20G and his own piggyback controller.

I would say properly managed as you outline (worth a check on a wideband AFR as well) that it should have reasonable reliability long term.

The main things to consider though are not det related at all, piston type and clearance with bore is far more important, I've mapped several cars up to the 400 bhp level on std internals and appropriate mods both with and without the factory ecu and I do consider it feasible ... however appropriate mods and mapping are a must, as mentioned det is only just one aspect of longevity.

bob

Thanks John, I forgot to mention the 20G.
The car is a UK Sti type (French one are the same ;-) ).
My concern was only about engine internals to be able to deal with such boost pressure in long term.
A agree AFR is of most interest, but as long as no det occurs and EGT keeps to a reasonable value, dosen't it means that fuel mixture is correct ?

Possibly, but EGT is only a proxy for AFR.

I think that careful attention to how you warm up and cool down has a major influence on engine life.
I would imagine that with the later style pistons it would be even more important to ensure the engine is fully up to temp before using serious boost.

Andy

Yes that's true, and be sure I always take care to engine warm-up and cooling.
It's now 5000km I'm running that boost level (except on race track where I turn down to 1.2 bar at high rev), without any problems.

My STi8 ran 1.6 bar without any problems (for 6000 miles before I sold it)but it tapered off slightly at the top end.

Conrad

1.6 bar !!!
I was convinced that the STi7/8 bore clearance didn't allow such a high boost level, especially over 4500RPM (at least for long term) !!!

On GEMS ECU mate, I believe piston to bore clearances only becomes an issue when big HP is made (assuming the clearances were correct from the factory in the first place), but I think each STi short motor will have different tolerances for sure (judging by the USDM 2.5 short motors anyway!) so each one will behave slightly different.

I am led to believe APS have there STi 7 in AUZ running in excess of 500 hp on standard internals but dont quote me ;)

Conrad

I have been running the 1,4-1,5bar(TD05/06-20G) for the last 25000km on mine,that´s only with the STI V7 shortblock without problems.

The engine uses around 0,5liter oil in around 3500km,but have done this since i got.

When The AVC-R is showing 280km/t on the "Autobahn" there is some blowby in the catchcan,but nothing alarming.

Skassa

I don't think the boost pressure is the best way of setting a limiting rating ? Some turbos make more power at less boost than others do. ie I used to run 1.7 bar on my MY95 to make 360bhp on a TD05, the TD05/06-20G later made 80 bhp more at only 1.45bar.
Some combination of boost/bhp needs to be considered as Xaviers 400bhp at 1.4 bar is generally going to mean less load and stress than Conrads 400bhp at 1.6 bar

Andy

Wish I had of got that Andy LOL More like 362hp :eek:

Conrad

Cyclinder temps are not completely down to afr, egt doesn't necesaarly follow that either.

Piston to bore clearance on a std Subaru engine is something to be wary of in ANY model and boost is not the limiting factor, thats a mechanical issue given the right mod state.

My EJ257 probably has one of the tightest bore clearances of a Subaru engine, although there is an obvious mistake in the service manual to make it difficult to tell. One day when I get it really hot I expect a piston to nip the bore, but then maybe not, the pistons are not supposed to expand anything like forged pistons do.

Is the issue the motors with forged pistons AND tight bore clearances? A cast or hypereutectic piston should cope with the tight clearance.

Did the new age STis from a certain vintage have forged pistons? Did they change to cast for MY03 or 04?

Interesting !
Anyone has an answer ?

The theory about the eutectics is great ... trouble is its not bourne out by the practice afaik. several eutectic'd engines have nipped the bores, even running std boost etc.

John there has been thread after thread about the piston types some of which you participated in.

Its all theory till proven in practice.

bob

Is bore nipping something you would expect the first time the piston expands excessively? Or after an interval?

Would bore ovalling cause oil usage?

Tightest EJ257 I've seen so far, had as little as 2 tenths of a thou' clearance. So tight, it was nigh on impossible to put the piston back in !

There also seems to be as much as a 1 thou' tolerance from bore to bore.

Mark.

Hi Xavier,

Is your's still pulling timing through 5-6k? Do you see the effect on EGT readings?

Thanks, Richard

Conrad,what did you have to do to your Sti 8 to get 400bhp...I've been reading part of the thread on Bob's Jdm with interest.On another thread you replied regarding headers...thanks...was thinking of fitting them to my04 sti that's already got ppp...Is there an easier route to more power,such as the 3 port etc and a remap etc with this later gen motor?...don't like the prospect of bore nipping...is this likely with 04 sti's?....
Also...Is uk 04sti the sti8....

Hi Richard,
The timming pulling problem between 5600-6200 rev disapeared with my AG-820 ECU ;-)
In fact, one month ago while still using my AG820 ECU, I was on race track and the protections on the up-pipe went vibrating so much that KC decreased down to -5° !!! I then went to the 4WD roller, and the dyno showed a 30 bhp hole between these rev range, everything fine below and above this range !!!
This fed me up and I then managed to get an AG821. Now with this new ECU I can smile again, even on race track : no more timming pulled. It's so nice :-)
So I cannot tell you wether that affect EGT or not.

In regards to 1.4 bar up to 6500 RPM and 400bHP, what's you opinion on reliability ? Did you experienced any problems (speaking about long term) ?

About piston's bore cleareance and material, don't you think (all) that even running 1.2 bar would have made the bore nipping problem appear ?

Running 1.4 bar only showed me EGT less than 870°C.

Glad to hear it :) I can't answer the 1.4 bar up to 6k5 question, all my cars run stock boost after 6k....I'm a wimp (who lives very near to DE's autobahns) :D

Richard

I run 03 sti .
Standard internals, runs 1.52-1.55 bar to redline(ecutek remapped). No problems as such.

rhodes_96,

who mapped your car ?

What else do you have fitted ?

Have you had it dynoed ?

Timing pulled because of up-pipe heat shield rattling?
:O

How did you fix that rattle? Did you simply pull off the heat shield, or did you replace the up-pipe with an aftermarket one?

RT : I simply removed the heat shield, just take care to the electric cables around there !

Rhodes, I can guaranty you that running 1.5 bar up to the red line, your engine won't last so much if you're running stock injectors, pump and FPR (and VF35 !).
I've just logged my car with WB O2 : the injectors are out at 6K rev with 1.5 bar (11.5:1), at 6.5k rev I reached 12.5:1 and 12.8:1 with 1.35 bar at 7k rev ! No way trying to enrichen the fuel mixture, it won't !!!

Yep see cars running 1.4-1.5bar here in OZ,like rhodes with SR40,etc etc tuned by MTR pulling around 230awkw no probs

I agree, but these car should have upgrade fuel pump, FPR and injectors. With stock 505cc injectors, you will be a lot too lean, monitored 13:1 on mine at 7K rev !!! It should last for about 20kmiles not more !