[Mk2] [Turbo] Forged internal advice required

[Dundee]

Hi folks, I've decided in the new year I'm going to fit forged internals so need some advice.
I have been looking at the various piston options available and need to know how to choose.
For or instance JE offer a 86mm 8.5:1 cr or a 86.5mm 9.0:1 cr what should I go for?
What bennefit would the larger piston give me other then a slightly increased displacment? Also surley the block would need boring out, how much of a job is this?
many thanks,

[3S Service Centre]

Pistons are selected to create the "perfect engine" to suits your needs.
You need to start by building a specification for the engine based on what you need it for, when you know what you need you can build the engine to suit.

Tell us what your building the engine for, what bolt ons you intend to use. Then you could receive some constructive advice from the forum members.

James

[Dundee]

Right, firstly apologies for my ignorance in the matter
I dont have a power goal as such, I'm not going to be using the car everyday now so I can afford the time for it to be off the road. The current spec is the basic bolt ons: intake, decat, 3" exhaust, intercooler, boost controller, fuel pump and fpr, my plan is to fit a charge cooler, bigger injectors, uprated turbo (not sure which yet) and an aftermarket ecu (Power FC) so forged internals seem to be the way to go.
What I want from the car is for it to be fast but usable so I dont want to fit a big laggy turbo but a smaller one that will spool quick but still make good power.
Hope this is the right sort of information

[RobCrezz]

Right, firstly apologies for my ignorance in the matter
I dont have a power goal as such, I'm not going to be using the car everyday now so I can afford the time for it to be off the road. The current spec is the basic bolt ons: intake, decat, 3" exhaust, intercooler, boost controller, fuel pump and fpr, my plan is to fit a charge cooler, bigger injectors, uprated turbo (not sure which yet) and an aftermarket ecu (Power FC) so forged internals seem to be the way to go.
What I want from the car is for it to be fast but usable so I dont want to fit a big laggy turbo but a smaller one that will spool quick but still make good power.
Hope this is the right sort of information

You want something like the GT28RS. As good spool as the ct20b but can make around 350-400bhp.

[Timsmr2]

Compression ratio will depend on how much boost you are going to run. Which will depend on how much power you want and what turbo you pick to do it. A smaller turbo running at higher boost will give you faster spool than a bigger turbo running at low boost to achieve the same power. Obviously the advantage of the larger turbo is it gives you more scope to increase the power.

IIRC getting the block rebored cost me £80 (a few years ago now) You will need to give the machine shop the pistons as well as block as they will bore each cylinder to the piston (especially important with JE).

[Dundee]

Right, firstly apologies for my ignorance in the matter
I dont have a power goal as such, I'm not going to be using the car everyday now so I can afford the time for it to be off the road. The current spec is the basic bolt ons: intake, decat, 3" exhaust, intercooler, boost controller, fuel pump and fpr, my plan is to fit a charge cooler, bigger injectors, uprated turbo (not sure which yet) and an aftermarket ecu (Power FC) so forged internals seem to be the way to go.
What I want from the car is for it to be fast but usable so I dont want to fit a big laggy turbo but a smaller one that will spool quick but still make good power.
Hope this is the right sort of information

You want something like the GT28RS. As good spool as the ct20b but can make around 350-400bhp.

Thats the exact turbo i've been looking at!


Now I've been looking into it around the 370-80 mark is what I'm going to aim for. I'm not set on JE pistons, I want to pick the right ones.

So if I go for a GT28RS, Power FC, charge cooler and bigger injectors, what would be the right pistons to go for and how much boost will I have to run?

Thanks for your help so far guys!!

[Timsmr2]

I'm running a fensport GT28BB Turbo @ 1.5bar With JE 86.5 pistons and getting ~310whp (~375fwhp).

Full spec is in my garage except the chargecooler has just been changed from a radtec to a 3S one (dont have any new figures since CC change) But it should give you a good idea of what mods you will have to do to achieve this kind of figure (probably not all the mods I have done to the engine are essential to get this figure).

Worth noting that once you start shooting for these figures its pretty much the same expense building a 350+bhp motor as a 450-500+ one as things like the turbo/injectors/ECU/gaskets/bearings/sensors etc will cost roughly the same.

As James said probably best to decide on the power figure and turbo first then you can work out the boost you are going to be running and the cr you want to achieve which will detremine you piston/HG choice.

[Rev 3 Kris]

Timsmr2- why did you change from the radtec ?

[Dundee]

I'm running a fensport GT28BB Turbo @ 1.5bar With JE 86.5 pistons and getting ~310whp (~375fwhp).

Full spec is in my garage except the chargecooler has just been changed from a radtec to a 3S one (dont have any new figures since CC change) But it should give you a good idea of what mods you will have to do to achieve this kind of figure (probably not all the mods I have done to the engine are essential to get this figure).

Worth noting that once you start shooting for these figures its pretty much the same expense building a 350+bhp motor as a 450-500+ one as things like the turbo/injectors/ECU/gaskets/bearings/sensors etc will cost roughly the same.

As James said probably best to decide on the power figure and turbo first then you can work out the boost you are going to be running and the cr you want to achieve which will detremine you piston/HG choice.

I guess thats just what I'm looking for!! I'm deffo going for a GT28RS, CC and PFC.
You have changed the Cams, this is something many others leave standard, what kind of difference do they make??
Would you say rods are a necessity? Alot of people seem to keep the standard ones?
Will the standard fuel rail be ok at this kind of spec?
What do you do about a down pipe when fitting this kind of turbo?

Thanks again!!

[Ryan S]

i was just going to ask, as well as pistons and conrods, is there anything you need to do to the crank or big ends???

[Dundee]

It was my intention to upgrade the bearing races on the big and small ends

[Ryan S]

It was my intention to upgrade the bearing races on the big and small ends

is this needed?? genuinely just wondering, i don't know the answer

[Dundee]

It's not a massive job and not very expensive so may as well

[Timsmr2]

I'm running a fensport GT28BB Turbo @ 1.5bar With JE 86.5 pistons and getting ~310whp (~375fwhp).

Full spec is in my garage except the chargecooler has just been changed from a radtec to a 3S one (dont have any new figures since CC change) But it should give you a good idea of what mods you will have to do to achieve this kind of figure (probably not all the mods I have done to the engine are essential to get this figure).

Worth noting that once you start shooting for these figures its pretty much the same expense building a 350+bhp motor as a 450-500+ one as things like the turbo/injectors/ECU/gaskets/bearings/sensors etc will cost roughly the same.

As James said probably best to decide on the power figure and turbo first then you can work out the boost you are going to be running and the cr you want to achieve which will detremine you piston/HG choice.

I guess thats just what I'm looking for!! I'm deffo going for a GT28RS, CC and PFC.
You have changed the Cams, this is something many others leave standard, what kind of difference do they make??
Would you say rods are a necessity? Alot of people seem to keep the standard ones?
Will the standard fuel rail be ok at this kind of spec?
What do you do about a down pipe when fitting this kind of turbo?

Thanks again!!

Yep alot of people havent upgraded the cams. The are a good mod as the higher duration cams will allow you to rev harder higher (if you know what i mean).

Rods again the stocks should do the job if you change the fasterners to arps but the cost difference is minimal between the cost of the arps and a set of Eagle rods (theres a set for £223.00 on ebay) plus the forged rods are not only strong but much lighter which helps the engine to rev more freely.

You'll probably be looking at ~800cc injectors so you will either need to rebore the fuel rail or replace it with aftermarket (i think a few of the affiliates on here offer rebored rails on an exchange basis).

As far as downpipe goes it depends you can buy a turbo kit with all the fittings or you can have a downpipe made up for you (which is what i did as I bought the turbo seperately)

[Timsmr2]

It's not a massive job and not very expensive so may as well

yep If you have the engine apart worth replacing all bearings/gaskets/pumps etc.

also the Duraglides are cheaper than stock toyota ones

[Chris]

With regards to the original question. If possible always stick to 86mm to ensure the block stays as strong as possible to reduce the risk of splitting at high boost. 8.5:1 will be better also as it gives you the choice later to fit a larger turbo and run higher boost without doing another build.

Cams are not needed for your aims at all. Use stock rods, crank etc just ARP fasteners throughout. As said, you might aswell do the job right and rebuild the lot as in new bearings, oil pump, water pump etc then you won't have to worry about reliability....in theory

[GTS GAV]

was basicly goin to say they exsact same thing as chris

im in the process of rebuildind my rev3 3S-gte

its best just to do the hole lot and not to risk it for future upgrades get it done properly once or it can cost you nearly double in the long run as a friend of mine found out the hard way
it would be best to invest in sum ARP bolts through out, and a set of full race bearings an thrust washers i went fo a set of ACL

i also as chris advised went for a 8:5:1 C/R but went for the cp pistons as they have great reviews and are better priced to others

iv heard rumours recently that eagle conrods hav been having clearences problems so thort about investing in sum carrillo h beams wich were nearly double the money to eagles but the carrillos can handle 250bhp a conrod 1000bhp overall and were so much much lighter and thiner stalks, same as you had a reasanable bhp goal of around 400ish but i had faith in nowing in the future if i decided on uping the power and bigger turbo, injectors etc i had faith in knowing everything was goin to be safe and strongm down bellow


are you also fitting new toyota oil pump, water pump etc?

[GTS GAV]

(CHRIS) i was havin a lil look on ebay and come across a car very similer to yours
hav you put her up for sale??

if it was yours the new buyer is goin to be a very lucky guy
i read your feature in banzai in think recently, looks like you put alot of time and effort into it with sum very rare goodys aswell

any way hope the sale goes well as im sure your be sad to see her leave

is there another jap car on the cards??? [Wink]

[Chris]

Hi Gav, the new owner to be (or not as the case is) cannot insure it So I still got the bloody thing. Debating what to do now. Re advertise or go buy some 1200's and see how much more power is left in it

Just a quicky though, no need for expensive rods, the stocks are fine. And yes you are right, Eagles are an ar$e especially with JE pistons. You have to either have the rod or piston machined to fit.

CP's do not need machining and are in my opinion a better piston. Loads quieter too!! JE's make a right noise when cold.

[GTS GAV]

arr thats a shame, i guesse he didnt check to see if he could get insured first

i also got advised that the je pistons were very noisy, i did sum serious research into pistons when i was looking for sum for my build CP came out on top by far

neva mind im sure some one will hav it off you soon enough the econemy is sort of the up again so should see more interest in it then, but for the time being why not stick in sum 1200cc in there sounds like a good idea to me see what shes got left before she goes

and im sure yourl be gutted when its gone, you goin down the jap route again

your feature in banzai was very interesting,and gave me lots of help whith my build,i would bit your hand off for you inconel mannifold and jun replica inlet mannifold

just wonderd because i couldnt remember are you runnin water injection
if so did you go aqua mist, or aem??

im thinking of buying the aem h20 hit but still unsure were the best place would be to fit the jet, eitha charge pipe, or in the inlet mannifold and wear on the inlet mannifold hav you any ideas on this buddy?