St205 Engine

[*rollaboy]

hi guys.

this post might be a little premature due to the fact that i havent actually gotten the engine running yet, but hear me out anyway.

i had an st205 engine fitted to my toyota sera using an mr2 turbo gearbox.

its a very low mileage engine with only 18,000 miles done.

its obviously got new belts, plugs, gaskets, fluids,filters etc

the mods are : front mounted ic, 3" downpipe & exhaust, and it is in the process of having an mbe engine managment sustem fitted. my next 2 mods planned are boost controller, and aquamist.

i know my car will probably already be on the limit, in terms of how much torque the front tyres will handle, but im curious to know how far i could push the standard engine seeing as i have invested in an expensive management system.

as far as i can gather from reading threads, around 300 bhp at 1.1 bar is the limit on the standard engine with standard turbo.

does my engine management allow me to run more boost with a different turbo???

when does the standard fuel system start to struggle??

how much boost can standard pistons take??

despite how this may look, im not actually caught up in hp figures, or into boasting down the pub.....

...id just like to know how much i could wring out of it if i wanted.

i would really prefer not to have to get the whole thing rebuilt, because its getting too expensive,

but would you guys reccomend to get a hybrid turbo or something to make the most of the mods i already have??

reguards,

rosco

[dawesy]

on std pistons i wouldnt go above 330bhp.

with a set of forgies, uprated injectors (800cc+), uprated fuel pump and the right turbo over 400.

please be aware though that reliability goes down proportional to the power going up! unless you are prepared to spend big money sorting out the issues with the block, dont go above 350-380. i did and i now have a 2 1/2 inch crack in No3 cylinder.

with a hybrid blower you should be good for 310-320 bhp at 1.1bar

as for the crank and rods, in a 2WD car i would say 500bhp @ the fly is relativly safe. im runnig 470 on std crank and rods, if its 4WD then i would knock it on the head at 450 bhp, and get a steel crank and carrillo rods. that said dont know of anyone who's broke either! watch this space :D

1.2 bar is the max on std pistons IMO, also if your ecu has individual cylider trim get the mapper to set it up so cylinders 2+3 run rich, aprox 11.1 AFR this may help the block.

and dont worry FWD is fine withover 380ftlbs (well in fifth gear )

[*rollaboy]

im not sure if my ecu has the capability to distibute the fuel like that tbh, but its the top mbe system so maybe i can. i dont thinkthe mapper has much 3sgte experience so your advice im sure will come in handy.

maybe i would rebuild the motor at some stage, but with such a low mileage engine, i rekoned it would be a waste to rebuild it before it was fitted.

to be quite honest, i think 280/300 hp in my light car will keep me satisfied for a long time to come.

would 19" tyres help traction, or isit all about width and tyre choice?? i know that you run 17s dawesy.

[Sketchy]

Assuming it's a stand alone ecu and not one of them bodge job piggyback ones, an aftermarket ecu can run whatever boost and turbo you want, you just need to get it remapped to suit the parts fitted.

You can't just swap the turbo on the stock ecu 'cause the fueling etc will be all wrong.

How far can you take the stock piston? Well that really does depend on how brave you are and how good you mapping is. It's not the pressure that'll kill the pistons it's heat and det, come to mention it large amounts of det will kill your pistons regardless of if you've got stock or forgies and it'll do it alot quick that you might think. Start running lean on full boost and high rpm and it's a mater of seconds before holes start to appear...

The general consensus is if you going above 330 get forgies put in. Having said that their are people out there happily running over 400bhp with stock piston. As I've said if you can keep the charge temps and det down then they'll be ok for a while at least. The ringland will go quicker than if you had forgies in but they won't just suddenly explod as soon as you go over x boost or y bhp.

The stock fuel system tops out around the 330-340 area, i've seen 359 running uprated fuel pump and increase rail pressure but it was at about 85-90% duty which is not where you want to be. Get a set of 850s in and your good for over 400

As Dawesy said the 3s-gte does have a common issue with cylinder wall spliting between cylinders 2 and 3.

It's caused by thin wall between the cylinders and surrounding waterways which in turn causes hot spots in the block which causes the cracking. This can be further excesperated by cavitation in the waterways. Water gets to hot, boils and causes an airblock which in turn cause hot spot to increase until something cracks. :ffs:

It's due to the casting tolerances in the block which leads to quite a variation in wall thinkness which has in turn lead to what you might have heard discribed to as Thinwalled and Thickwalled Blocks.

Unfortunately there no way to tell what your wall thickness is without stripping the block and getting it ultrasounded Thickwalled is considered as one where the cylinder wall thickness is above 4mm at it's thinest part. Thinwalled ones can be as low as 2mm.

[*rollaboy]

Assuming it's a stand alone ecu and not one of them bodge job piggyback ones, an aftermarket ecu can run whatever boost and turbo you want, you just need to get it remapped to suit the parts fitted.

You can't just swap the turbo on the stock ecu 'cause the fueling etc will be all wrong.

How far can you take the stock piston? Well that really does depend on how brave you are and how good you mapping is. It's not the pressure that'll kill the pistons it's heat and det, come to mention it large amounts of det will kill your pistons regardless of if you've got stock or forgies and it'll do it alot quick that you might think. Start running lean on full boost and high rpm and it's a mater of seconds before holes start to appear...

The general consensus is if you going above 330 get forgies put in. Having said that their are people out there happily running over 400bhp with stock piston. As I've said if you can keep the charge temps and det down then they'll be ok for a while at least. The ringland will go quicker than if you had forgies in but they won't just suddenly explod as soon as you go over x boost or y bhp.

The stock fuel system tops out around the 330-340 area, i've seen 359 running uprated fuel pump and increase rail pressure but it was at about 85-90% duty which is not where you want to be. Get a set of 850s in and your good for over 400

As Dawesy said the 3s-gte does have a common issue with cylinder wall spliting between cylinders 2 and 3.

It's caused by thin wall between the cylinders and surrounding waterways which in turn causes hot spots in the block which causes the cracking. This can be further excesperated by cavitation in the waterways. Water gets to hot, boils and causes an airblock which in turn cause hot spot to increase until something cracks. :ffs:

It's due to the casting tolerances in the block which leads to quite a variation in wall thinkness which has in turn lead to what you might have heard discribed to as Thinwalled and Thickwalled Blocks.

Unfortunately there no way to tell what your wall thickness is without stripping the block and getting it ultrasounded Thickwalled is considered as one where the cylinder wall thickness is above 4mm at it's thinest part. Thinwalled ones can be as low as 2mm.

thanx for the detailed reply. as i mentioned above, it IS a propper standalone system, and with my fmic, and planned water injection, i think im doing all i can to lower the intake temp.....if there are any other methods, please let me know. we only have 95 and 97 octane fuel over here, but seeing as this car will only be used weekends, im sure i could afford to use additives or order race fuel (if thats not a daft idea).

oh yeah, and its not a race car or a dedicated drag car, so i wont be thrashing it for extended periods.

i think you guys have more or less given me the info i was looking for, so thanx

[dawesy]

idewly mate you need to stick with a 15-16"rim but as wide as you can fit under the arch on the front as this will help traction, 19" rims will kill acceleration. im looking at changing the front brakes back to std for drag days so i can fit some propper drag radials

[*rollaboy]

haha, even the 17's were lost in my arches....ill need to have at least 18" for looks.