twin turbo set up

[ford100ev8]

i have a rover v8 3.9 efi ,i want to keep the efi and fit twin turbos , i am looking for about 400bhp , what size turbos would i need to get , i can make my own manifolds as i am a fabricator, tig welder by trade , i just need to find out about the inlet manifold , any info would be much appriciated , thanks

[kiwicar]

Hi
there are two ways to size the turbos, calculate the airflow requirments for the boosted engine, get a load of turbo maps and plot the requirments onto the maps find the best fit. there are various books that will take you through the process, if you decide to go through this process I can surgest a couple of books.
The second way is to find a 2 litre ish car that produces about half your target output over the rev range you are after and get 2 turbos for that model.
what I would advise is that you pay particular atention to the base tune of the engine, aim for a cam/head inlet manifold combination that will give you about 220 bhp and then boost it to about 15 psi. be carefull not to drop the CR too far, I would recommend the turbo cam from Real steel for this and make sure the squish band is not sacrificed to lowering the CR use a nice big intercooler. . . should be fairly easy to achieve what you are after.
best regards
Mike

[ford100ev8]

so i am looking at two t3 turbos of 2 lt cars , do i need to fit forged pistons ? what other internal mods need to be done , also what gearbox would be best , its going in my ford 100e , thanks

[kiwicar]

Hi
If you are going for a modest output like this you may get away with rover pistons but I think they may be marginal. as usual it depends on budget and how much you are prepared to do and how confident you are in sorting out the details.
Forged rover pistons are the simplest solution as you just buy them and install but at £550 to £650 plus vat you pay for the convenience.
Ford mod 3.7" froged pistons (or the +20s) with the deep dish are about half this even when you have imported them, you need to shop around and be certain what you want before you buy, you need to work out what CR you want and have measured your heads combstion chamber before you buy we can help but there are several threads on here to read through first. you will also need to get the rover rods bushed, or find a rod with the ford pin size that you can use on the rover crank.
Chevy 305 pistons and small journal chevy rods, but you need to get the block bored to 3.736" and this is not ideal on a boosted engine, again at modest boost this is not a big issue but worth considering. again much cheeper than forged rover pistons.
I would get a set of mildly ported heads with bigger exhaust valves and a copy of something like this.

Apart from that it is pretty much normal tuning stuff, radius all the oil ways, select a suitable cam, clean and prep the block, I would use arp studs for top and bottom end and choose a sensible CR of about 9:1 with a big fat intercooler.
As for 'box. . . Manual or auto? are you going to drag race it or just a daily driver?
Best regrads
Mike

[ford100ev8]

i would realy like manual gearbox , i think i would go with the rover v8 forged pistons , i have got about 2.5 grand to put in to it , also can i still use the standard 3.9 efi plenum , thanks

[kiwicar]

Hi
Ok, I would replace the rod bolts with ARP studs then, and polish the rods, ballance them and get them shot blasted, ballance the bottom end stick on a light flywheel (don't lighten a standard one!). You can use the standard inlet manifold, but as you are an ally fabricator couldn't you make a nice statment piece of a fabricated split plenum manifold with the outer and inner cylinders on each side fed from opposite banks, it would even up the pulses in the inlet, just a thought and it would look dead cool!
as for manual box, a T5 with a TVR bell housing or a R380 2wd would be the simplest, I wouldn't bother with an LT77 it would go bang.
Best regards
Mike

[ford100ev8]

brillaint , thank you for your info and help

[stevieturbo]

i have a rover v8 3.9 efi ,i want to keep the efi and fit twin turbos , i am looking for about 400bhp , what size turbos would i need to get , i can make my own manifolds as i am a fabricator, tig welder by trade , i just need to find out about the inlet manifold , any info would be much appriciated , thanks

Forget ancient T series turbos.

A pair of Subaru TD04's are compact, will easily do 400+ and spool nice and early. And best of all, you'll buy them for less than £100 each

Im sure there is a guy on this forum who has already used a pair. If not here, he is defo over on pistonheads.

As for inlet manifold, just use whatever you have.

With proper fuel/spark management, standard pistons and compression ratio should be fine for a low boost setup. Or fit a thicker head gasket to drop the CR a bit more safety.

As for engine, You dont need to do anything really. The std crank and rods are fine. I ran a 3.9 twin turbo for a few years on std bottom end albeit with forged pistons with the crown machined down to lower the CR. ( I'm not suggesting you go down that route, it's crude and the pistons were already in the engine from a n/a build ) But it didnt cost any money, which was more important at the time !

Just get some ARP head studs, and ARP rod bolts or main studs wouldnt go astray. But not essential either.

Heads are entirely up to you. But I'd struggle to see value for money going overboard with them. A mild port and throat cleanup and some better valves and springs would be more than adequate.

[spend]

Heads are entirely up to you. But I'd struggle to see value for money going overboard with them. A mild port and throat cleanup and some better valves and springs would be more than adequate.

I agree on the basis that the port separation becomes very marginal when installing larger valves.

I'd also consider thermal coatings to Pistons & heads before messing with different rods / pistons / head spacing malarky. Using a 4.6 is probably a better starting point though.

[kiwicar]

"Using a 4.6 is probably a better starting point though."

He already has a 3.9. . . how is 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 ???
400 BHP is easily achievable with a 3.9, he has no need to blow half his budget or a 4.6 when he has an engine already that will achieve what he wants. I still feel the rover pistons mey be marginal, but as Stevie is convinced you can chop the tops off and use them for a 400 bhp engine then go with that, it saves a packet.
Best regards
Mike

[ford100ev8]

where would you recomend to get forged pistons from , thanks

[stevieturbo]

Depends really.

Most manufacturers will make a custom set of whatever you want. Arias, JE, Accralite, Mahle, CP Wiseco, Omega etc etc etc

Dave at Performance Unlimited should be able to get you whatever you need.

[kiwicar]

Hi
pretty sure Omega did a forged piston for the rover, I would get in touch with them http://www.omegapistons.com/performance-pistons.php
Cosworth also used to make them.
V8 developments may be worth a go though their website is mainly short and long block motors.
Mike (boosted performance) who posts on here is probably worth an ask, he may carry them http://www.boostperformance.co.uk/
JE developments carries 3.5 die cast omegas, he may get the 3.9 forged ones.
V8 tuner carries them and his prices include Vat! good job too!! http://www.v8tuner.co.uk/product.php?id=54
I said they were pricey things.
Best regards
Mike

PS as Stevie says all the US manufacturers will make them to order, for the price of the ones from V8 Tuner you could probably get a set mabe by JE in the states, but then you would just want to put them on the mantle piece and admire them.

[spend]

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?

[stevieturbo]

I still feel the rover pistons mey be marginal, but as Stevie is convinced you can chop the tops off and use them for a 400 bhp engine then go with that, it saves a packet.
Best regards
Mike

That isnt what I said.

I said I had previously chopped a set of forged pistons and used them. I also said I would not recommend this approach. But it worked for me, and cost me nothing as the pistons were already in the engine.

There is a difference doing something yourself being fully aware of the risks, and suggesting others do the same who may not be.

But a lot depends on what he already has. The design of the pistons etc.

I did use a totally standard 4.6 shortblock and pistons for some time when turbocharged and would have no hesitation in recommending that. It's a good strong platform, the pistons while cast, are a sensible and strong design for boost.

Ultimately one of the most important factors is tuning. Without proper fuel and spark control, you risk damaging even the best internal components.