The V8 Owners Forum -

hi guys,
should be picking up my new toy a tr7 v8 - its got a 3.5 with twin su's so, im assuming basic 150 bhp spec.

Im going to keep it like that for a bit, but planning forward, if i were looking to get to 250bhp at the fly, what would be my best route - stick with the current 3.5 or go for a 4.6 block with headwork etc?

any thoughts with approx cost.

cheers

Cheapest - 4.6 with a set of big valve heads

Best - 3.5 with parts to allow it to rev past 7500

I have a 3.9 that runs 256 hp at the fly.

Engine was bought new £4000
Sent tqo J Eals for balance, head work, plenum work, cam, lifters etc cost £6000

So engine in total was £10 000

The 256 hp is at 6250 rpm

By the way I did not go that route it was the previous owner of the car. A Ford mill would have easily given 350 hp at half that price. But I bought a half built project and could not see a reason to throw away a new motor!

Ian

Hi
this is about your cheepest way to a genuine 250 bhp http://www.ebay.co.uk/itm/CHEVY-L33-V8- ... 929wt_1170
Best regards
Mike

Chris, as a suppliment to my post on your ignition thread and of course bearing in mind the following article on power losses was originally aimed at efi cars, there are, nevertheless, loads of good points to address in order to ELIMINATE any existing power losses that may exist in your set up BEFORE trying to add power output.

Have a butchers and see what you think:

http://www.vintagemodelairplane.com/pag ... wer01.html

Mine makes 248bhp @ 5750rpm and pulls to 6300rpm

It's a 3.9 intermediate block, non cross bolted.
Kent H214 camshaft.
NCK ported TVR heads (standard valve sizes)
Ported 38mm Inlet manifold with carbon trumpets.
CR around 9.45:1
Megasquirt2 fuel and sparks.

It's a nice engine to drive, comes on cam from about 3250rpm, pulls from idle but is a little bit wooly on light throttle loads at idle to 1800 rpm ish but generally fine for around town.

I'm looking to go a bit wilder on the cam to shift peak power to 6kish, not sure if the H234 would be too much

Hi
Yes but did it cost you £1700?
Best regards
Mike

You could buy an 4.3 engine from a TVR Chim like I did. Setup by Mark Adams at Mech Repairs Dyno and had just over 260bhp. Ok not the 280 that TVR claim but very close. Think it cost me £2500 but included a T5 box as well.

"You could buy an 4.3 engine from a TVR Chim like I did. Setup by Mark Adams at Mech Repairs Dyno and had just over 260bhp. Ok not the 280 that TVR claim but very close. Think it cost me £2500 but included a T5 box as well."


Fair enough, I still would rather go with the LS but that could be brand bias
Actually with the price of Lexus engines at the moment. . . I think for 250+ bhp they are even cheeper!
Best regards
Mike

Hi Mike, If I was starting again then it would be an LS for me as well.

Bought mine from a well know salvage place up near Warrington and they actually give a gurantee. Compared to what some people spend think it was a very good buy as it came with all ancillaries as well

regards
Reg

kiwicar wrote:Hi
Yes but did it cost you £1700?
Best regards
Mike

Well most of it came with the car, i've only added the Megasquirt and the carbon trumpets, which came to about £500 for both.

If you were starting from scratch i'd guess a similar spec based on a good used 3.9 would cost £2.5k if you were buying the ported heads and ported inlet new.

If you had a bit of time to wait for ebay bargains it could be substantially cheaper. I got a set of big valve heads for £280 for example rather than 1k+ new.

Cheers
Ben

£1700 would not get you 250BHP turning the back axle through a 5 speed gearbox. Its just not a fair comparison - As you would need ECU's fuel pumps swirls tank mods headers, flywheel clutch gearbox tunnel mods - engine mounts and the list goes on to cost more like £6000 to get an LS equiv in a TR - Starting from scratch with a 4 pot - I would still bet that at the end of the day it would be cheaper to get 250BHP with a Rover.
300+ BHP and you may have a case

kiwicar wrote:Hi
this is about your cheepest way to a genuine 250 bhp http://www.ebay.co.uk/itm/CHEVY-L33-V8- ... 929wt_1170
Best regards
Mike

What will that ally LS engine put out as standard?
What can it be tweaked to on stock internals ?
Can you chuck all the gubbins off it and fit a hoofing great Carb and Blower?

kiwicar wrote:Hi
this is about your cheepest way to a genuine 250 bhp http://www.ebay.co.uk/itm/CHEVY-L33-V8- ... 929wt_1170
Best regards
Mike

Bear in mind Mike that does not include and ancillaries, clutch, flywheel or gearbox. So at least double that £1700. Still, I'd take that over an RV8 any day.

Or, Lexus V8 1UZFE. 260bhp out fo the box and can be forced to 500bhp on standard internals. Autobox only though without expensive adapters.

Hi Perry
What will that ally LS engine put out as standard? I think stock on that engine is actually 260bhp.

What can it be tweaked to on stock internals ? A cam change to something that is still very road drivable takes you over 300 BHP, change the valve springs and go to a cam of about the same timming as you have on your current engine and it would be over 350 all on stock bottom end. you can clean up the head castings and gain about 20bhp more get them CNC ported and they will liberate a lot more as you increase valve timming bottom end should be good for about 425 to 450 on stock pistons, change to forged pistons and better rods and you could probably see 650 on stock crank.

Can you chuck all the gubbins off it and fit a hoofing great Carb and Blower?
Your 4-71 would need a different inlet manifold and spinning a bit faster but would probably deliver 8 or 9 psi of boost on a base 350-400 bhp spec engine, it is a little difficult to say as these heads flow about 280 cu ft/min in stock form and I suspect the the engine would consume so much air that the 4-71 would struggle to produce a highe enough level of back pressure to get you to 12psi. you would probably see about 650 bhp on only about 9 psi of boost and need a 6-71 to get it to 12psi. . . and a corrosponding amount of power increase.
Best regards
Mike