twin turbo set up

kiwicar · Post by **kiwicar** » Sat Feb 04, 2012 8:07 am

spend wrote:
kiwicar wrote: spending £1000+ on finding a 4.6 and top ha linering the thing a better starting point when he only has a budget of £2.5 ???
Who in their right mind would spend £1000 on a block that need linering?

Do you think you are going to get a set of forged pistons for much less than that anyway?

Nobody said anything about about spending £1000 on the block that then has to be top hat linered.
But £200 odd on finding a used 4.6 block, hot tank the thing £20, £800 to £900 for liners and fitting and vat on that and you are well past £1000. The point still stands, starting off by buying a 4.6 when the 3.9 he has will do the job is a poor way of spending a £2.5k budget.
best regards
Mike

stevieturbo · Post by **stevieturbo** » Sat Feb 04, 2012 9:47 am

I see nothing wrong with a good solid 3.9 block, crank, rods etc for this. And some suitable pistons

DaveEFI · Post by **DaveEFI** » Sat Feb 04, 2012 10:24 am

Is it easy to get a bare block tested, and how much would it cost?

kiwicar · Post by **kiwicar** » Sat Feb 04, 2012 5:11 pm

stevieturbo wrote:I see nothing wrong with a good solid 3.9 block, crank, rods etc for this. And some suitable pistons

Mike

neal1980 · Post by **neal1980** » Sun Feb 05, 2012 1:09 pm

Im using a 4.6 top hat cross bolted engine. It has ARP studs and the standard cast pistons. Im using de-compression plates and currently boost to 10psi, will be heading towards 15psi at the end of this month.

Its me with the 2x Td04 subaru turbos.

ford100ev8 · Post by **ford100ev8** » Sun Feb 05, 2012 1:44 pm

sounds good , i am thinking of geting the td04s aswell , they seam very cheap , how have you made the manifolds up for these , thanks

Fozwanger · Post by **Fozwanger** » Tue Jun 19, 2012 12:38 pm

I'm interested in this and peoples opinions.
I'm building a new 3.9, stock pistons, rods and crank, JE stage 2 (whatever that actually means) heads that'll give me a CR of 8:1, blower / turbo cam, running a converted Janspeed TT set up that I had on my previous 3.5 TT moggy.
I'm looking to run about 10 - 15 psi boost and hoping for about 350 - 400 hp.
The TT set up I used before on a totally stock 9.35:1 SD1 motor, running 8.5 psi boost, thrashed the nuts of it everywhere, dyno'd at 200 hp and 200 lbs/ft at the wheels and ran a 12.3 sec 1/4 mile.
Did 6000 miles in less than 6 months, only problem I had was the spark plugs kept coming loose.
I think a 3.9 is a better option that a 4.6 due to the liner issue, also I would go for a block that is NOT cross bolted as this allows the bottom end to move slightly and prevent stress fractures in the block. The 5.0 race TVR boys used to use cross bolted and most have moved away from them to the 3.9 blocks as they do not suffer with such failures.
I would've liked forged pistons but haven't got the £700 for a set. If it's a race car then I would fit them but as it's a street car it's gonna spend most (about 99%) of it's life on part throttle hence the reason I didn't get them.
Any pics?

kiwicar · Post by **kiwicar** » Tue Jun 19, 2012 1:45 pm

you can get ford mod 3.7" forged pistons in various dishes from about 24 cc to flat top, for about $450 to $470, by you've imported then and paid the vat and duty you are looking at £550 tops (if you can get someone to bring them back in their lugage it is a lot cheeper!) You would need to bush the rover little ends for the ford pin. I wouldn't drop the CR so far though, 8.5 to 8.75:1 would be better, especially with rover heads.
Best regards
Mike

thewedgeshop.com · Post by **thewedgeshop.com** » Tue Jun 19, 2012 4:21 pm

Fozwanger wrote:The TT set up I used before on a totally stock 9.35:1 SD1 motor, running 8.5 psi boost, thrashed the nuts of it everywhere, dyno'd at 200 hp and 200 lbs/ft at the wheels and ran a 12.3 sec 1/4 mile.

What did you mean by this? Thrashed nuts and bolts everywhere?

Thanks
Clint

Fozwanger · Post by **Fozwanger** » Wed Jun 20, 2012 5:00 am

thewedgeshop.com wrote:
Fozwanger wrote:The TT set up I used before on a totally stock 9.35:1 SD1 motor, running 8.5 psi boost, thrashed the nuts of it everywhere, dyno'd at 200 hp and 200 lbs/ft at the wheels and ran a 12.3 sec 1/4 mile.
What did you mean by this? Thrashed nuts and bolts everywhere?

Thanks
Clint

Clint,

Drove it like I stole it

Jeff

ford100ev8 · Post by **ford100ev8** » Wed Jun 20, 2012 7:55 pm

If I went for the ford mod pistons , do I need to get the block machined as I would like forged pistons and have family in Canada who can send me them ,

Boosted LS1 · Post by **Boosted LS1** » Wed Jun 20, 2012 8:25 pm

Fozwanger wrote:I think a 3.9 is a better option that a 4.6 due to the liner issue, also I would go for a block that is NOT cross bolted as this allows the bottom end to move slightly and prevent stress fractures in the block. The 5.0 race TVR boys used to use cross bolted and most have moved away from them to the 3.9 blocks as they do not suffer with such failures.

I'm not sure about some of this. The race cars of old used to use 'X' blocks which were the pukka 3.5 crossbolted blocks with small journal cranks. They're still highly desireable in some circles. Also, I would have thought that the last thing you want in a block is flex as this would cause stress fractures and cap shuffle, two things cross bolting's supposed to address? A 3.9 has a shorter stroke so will be revvier then a 4.6 or less stressed at 6k then a 4.6 at the same revs. That could be nice.