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PostPosted: Sun Jan 24, 2016 4:09 pm 
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Joined: Sat Jan 23, 2016 11:16 pm
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Hi ive just bought a celica st185 gt4, the car was built by a motorsport enginner, the spec from the advert is below: Its had a recent full rebuild of the engine , new turbo from an st202 gt4, runs and drives perfectly but need an electronic boost controller, got one ordered but am unsure of what boost level i can run? Any help would be appreciated.

The 3sgte engine was rebuilt and blue printed where ever possible:
Crank polished and balanced and oversized shells fitted.
Cylinders honed fresh rings fitted. (only honed to try to minimise chance of blow by)
TTE 1.4 alloy head gasket fitted to help her take a little extra boost as advised by Martin kingston.
All block oil galleries cleaned properly.
Cylinder head faced to a minimum. (only to a minimum to avoid any further compression adjustment)
Cylinder head inlet and exhaust outlets matched to manifolds to help her breath.
Valves and seats cleaned,ground and lapped.
Valve clearances shimmed and all valve and cam assembly assembled using active8 friction reducer.
New pumps fitted.
New Cam belt fitted (obviously)
New head bolts fitted and sequenced correctly
All new gaskets fitted and where necessary Dirko'd
All machining processes carried out by Wier street engineering.
All assembly carried out painstakingly by myself and Martin Bolland in a clean and controlled enviroment for nothing else but performance!

Turbo,Exhaust and intercooler and cooling:
The original ct26 turbo had excessive spindle float so the decision was made to upgrade to the later st205 orignated ct20 Turbo the original cast exhaust manifold looked floored in design to us which I think was due to space limitations so a new tuned length manifold was CAD designed and fabricated using plasma cut flanges and stainless tubing using a 4 into 2 configuration to help maintain pulse accelerated spool up. The manifold was wrapped in magma infused exhaust wrap to help keep manifold temps high and under bonnet temps low.The turbo was raised and clocked the battery was re located to the boot to make way for our fabricated air box this gave a beautiful in line induction tract.

The old Catalist was scrapped and a new down pipe fabricated using two separate down pipes one narrow for waste gate gases and one larger for exducer exhaust gases we kept them separate to help prevent any unwanted turbulence the pipes re join smoothly a little forward of the sump. The air con pump was scrapped including all pipe work,condencer the old radiator scrapped including all pipe work the largest diameter radiator possible was researched at a local parts supplier which happened to be one from a Landrover disco so a brand new one was ordered and fitted along with a new alloy header tank. A trip to the local scrap yard got us a mint front mount inter cooler with a decent size core. Stainless custom pipe work keeping the smoothest possible curves was designed and fabricted and wheel polished before fitting. All pipe joints that had to be rubber were replaced with silicone wherever possible. The original Bailey none recirculating dump valve that came with the car was wheel polished and placed up stream of the intercooler to help reduce intercooler temps. The intercooler was placed right up front and bumper baffles fabricated to force air into the intercooler and rad area to help keep temps low. A low profile auxiliary fan was also fitted.


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PostPosted: Sun Jan 24, 2016 4:48 pm 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
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Hi and welcome to the club.

It looks like some good work has been done and some original thinking.

There are a number of things on the 185 which limit the boost that can be run to stay reliable.

The headgasket is one of the main weak points and resulted in the death of many 185's as the garage bill for changing it was typically approaching the value of the car. The usual trick is to use the steel head gasket which is standard on the st205 as these are cheap as chips.

The intercooling on the air to air versions is terrible. The water chargecooler use on the CS/RC version is much better but still not ideal in it's standard form.

It seems the above two have been dealt with.

The next limiting factor, mechanically, is the standard piston. It is generally considered that 1.2 bar (fuel cut limit on a st205) is about the safe limit with these. If it were me, I would have swapped to forged pistons while the engine was apart as the cost is no higher than the standard ones. That is unless I was intending it to be a high milage road car.

The other limiting factor on the 185 is the whole engine control setup. The injectors are only 440cc as aginst 550 on the st205. These will probably reach their limits by 1.2 bar of boost. The earlier 185 ecu's (most of them) have a lower (0.8BAR from memory) boost limit. The other problem is that they are normally mapped very very rich as safety margin for the poor intercooling.
There are many options for ECU, each with their own merits, accoring to the planned usage for the car. Either a piggyback to retain the safety features of the standard ECU but tweak the mixture and timing or a full aftermarket standalone. This subject has been covered many times on here so worth having a dig around in the modifications section.

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PostPosted: Sun Jan 24, 2016 11:40 pm 
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Joined: Sat Jan 23, 2016 11:16 pm
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Thanks for the input, think ill add the electronic boost controller and just go with a bar of boost to start and see how the car gets on with it..... Car won't boost past 7psi at the moment, which makes it very tame!

The guy who owned it before me has done so much good work, all i need to do is resolve the boost issue, makes new seat frames as the current ones sit me way to high up in the car (its fully stripped with buckets and harnesses) then get the car plasti dipped white, then get it out track.


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PostPosted: Fri Mar 04, 2016 7:28 pm 
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Joined: Thu Oct 06, 2005 11:46 pm
Posts: 42
Location: Wales
Car Model: None
Fuel injector duty cycle and intake temps. will limit your maximum boost pressure


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