Fast Road Car Engine Rebuild

[Jak_Vts]

Basically I am looking to put a new engine into my GTi later this year, the original idea was to put a low mileage JP4 engine in, but im now thinking or rebuilding a J4 engine. Im looking for a fast road spec cammed engine ideally what spec would people recomend? It will be used on track but not solely on it. Would be uprated pistons be overkill on a cammed engine? whats the wildest cam I could run on an everyday car? What other work would i need such as headwork etc.It will obviously be run with a Standalone ECU likely the predator. Any help/reccomendations would be great!

[raunchz]

go with high compression pistons whilst it's apart - will future proof yourself.

Some ph3's, standalone and it'll feel pretty quick - Ideally you'd want TB's to go with them to make the most of the spec

[Jak_Vts]

go with high compression pistons whilst it's apart - will future proof yourself.

Some ph3's, standalone and it'll feel pretty quick - Ideally you'd want TB's to go with them to make the most of the spec

thanks are throttlebodies ok for everyday use? I imagien they would if mapped etc?

Would a ph4 cam be too wild?

Also what hi-comp pistons would you reccomend? and any other internals worth upgrading while its apart?

Would ph3's, standalone and hi-comp pistons see over 150bhp?

Sorry for all the questions trying to learn as much as I can before i start buying parts and building the engine in August

[raunchz]

Throttle bodies are fine for everyday use, I've been using mine for over a year and used the car for commuting last year and they were fine - allbeit a tad bit noisy :)

A PH4 (Newmans camshaft) wouldn't be too wild. It's generally regarded as the wildest camshaft that you can use whilst keeping the standard Saxo hydraulic followers - most people fit Newmans valve springs with the PH4's too.

It's hard for me to recommend high compression pistons - Wossner pistons seem to be the most common and I don't recall people having any problems with them.

Regarding any other parts to upgrade, you could fit some ARP rod bolts for piece of mind.

PH3's, standalone and high comps should be knocking on the door of 150bhp - suppose it would depend on your exhaust setup and intake setup, and mapping. I'd personally go with throttle bodies if going standalone and high comp pistons. Purely so you only need to map the engine once, and it'll run a lot smoother and nicer than on a standard inlet.

[JoshB]

If 150bhp is your target I wouldnt waste money on uprated internals.

A PH3 cam, decent headwork and a good map will see you 150bhp, with stock internals and no need for throttle bodies either.

[Jak_Vts]

thats great thanks! Been looking on here
http://www.lioliosracing.gr/pdf/Newman/Citroen.htm

when it says cam will not run on standard injection does that mean you need a remap or more powerful injectors?

Thinking about Spec, I may stay away from throttle bodies for now and have
PH4 Cams
Newman Valve springs
Hi-comp pistons
ARP Rod bolts

Anything else that needs to be uprated?
What about head work?

[raunchz]

I was only trying to future proof the engine if he's rebuilding the J4 engine - especially with cams, standalone.

They are an added cost - probably only cost you around £400 (as rebuilding the engine you'll hone the block and fit new piston rings anyway)

If 150bhp is the target, and no further then I agree with JoshB - no need to take things any further, but as can be the case with modifying/power - you can always want more :)

[raunchz]

thats great thanks! Been looking on here
http://www.lioliosracing.gr/pdf/Newman/Citroen.htm

when it says cam will not run on standard injection does that mean you need a remap or more powerful injectors?

Thinking about Spec, I may stay away from throttle bodies for now and have
PH4 Cams
Newman Valve springs
Hi-comp pistons
ARP Rod bolts

Anything else that needs to be uprated?
What about head work?

You'll ideally need TB's for PH4 cams - I wouldn't run PH4 cams on standard inlet.

I'm not saying that it's no possible, but I can imagine the engine would be a right pig to drive and map (speed density)

You'll want bigger injectors with PH4's too (something around the 280cc mark - so gti6 injectors or 172/182 injectors)

I think Newmans mean that it'll need a remap for the cams to work + will probably need bigger injectors.

[jeffchiz]

i was gonna say i wouldnt use ph4's with standard inlet, if you dont want expensive jenvey bodies you can get gsxr bodies with a manifold ready to bolt on for about half the price

[KamRacing]

The problem with the PH4's without throttlebodies is down to getting the car to idle and pass emissions.

[Jak_Vts]

Ideally 180bhp is my target, but I'm not getting hung up on figures just want gd power with a good torque curve, passing emissions wouldn't be an issue, it may have to be throttle bodies then do people rate the atpower ones?

I was only thinking of uprating internals, for more power in the future because I know what I am like, I will rebuild it with standard internals and want more before the end of the year! But with what you are saying I think I have 2 options a cammed well breathed engine looking about 150bhp obviously this is the cheaper option or I can put more money in and go down the throttle bodies route straight away.

Also I thought hi-comp pistons would give me better torque too, which is another reason I am considering them, that correct?

[KamRacing]

There are lots of happy people with the AT power ones and GMC usually has them on good discount.

[Jak_Vts]

ok thats good the only thing im thinking is if I go down the throttle body route i also have too account for things like a LSD it all adds up! A well setup cammed engine is appealing to me atm!

[AndySAXO]

to target 180 then ph4 and bodies is about where it at for that.

at power bodies are good, i am using atpower bodies i am very heappy with them.

andy

[webby]

I will be building my engine over winter for a similar spec.
It's going go consist of
fast road camshaft
over sized wossner pistons
and a decent exhaust system
maybe if I have time a redesigned inlet plenum and inlet runners using a larger single tb.

[Jak_Vts]

I will be building my engine over winter for a similar spec.
It's going go consist of
fast road camshaft
over sized wossner pistons
and a decent exhaust system
maybe if I have time a redesigned inlet plenum and inlet runners using a larger single tb.

So your not going down the throttle bodies route? what sort of power are you expecting from that?

[webby]

It's only worth while for me because all it will cost me is time to design the intake. Materials are cheap and if it goes tits up it will have oy cost me time.
The s1600 cars ran a single tb setup due to the regs granted with much wilder cams than I want to run which changes the design somewhat.

I'm hoping for around a usable 160hp with a flat torque curve