useful JP4/JP4S setup for 170bhp?

[sammys]

hey guys, my engine mod is in planing now. At moment I use a TU3 KFX engine and want a JP4 or JP4S.

would prefer a JP4 or JP4S because the old J4 is pretty rare here in germany!
I know, the JP4S have the same head as a JP4, both have bigger valves but the JP4S does have better cams, better springs and (i heard) a other crank shaft than a JP4? Thats all and correclty?

My plan: using a JP4 or JP4s engine with the alloy manifold, Clio RC throttle body incl adapter, standart J4 ecu, j4 engine loom and running with a Rallye gearbox. I think it's enough for ~130bhp?

I ask myself which other mods are useful! Would like to have arround 170-180bhp, which setup is useful for this performance yield?

thanks

[Ross]

Jp4s difference to jp4 is cams, springs and inlet really. Crank is the same to my knowledge.

You should see 130hp no problem from that setup with a free flowing exhaust and filter.

For 180hp you'll need a good amount of modifications. ITB's, cams (PH3's etc) will get you close with a good map (maybe 165-170) but for 180hp you're probably looking at a high compression setup with wilder cams, like PH4's etc.

AlexB still has his 180ish engine for sale - it would be a lot cheaper to buy that than buy all new parts for your build really. Have a look in the for sale forum area. It's a good engine setup.

[PSILOS]

it is difficult to use throttle bodies with standart ecu.

[Ross]

Not when remapped. But standalone is more flexible.

[welshpug]

you don't NEED itb's for 180, but will make for a much more rounded performance and easier to drive.

the R2 spec C2 rally cars ran 180 bhp on standard inlets, standard rods and crank, worked head, uprated valve springs, solid lifters and cams, and forged slipper type pistons.


All TU5 crankshafts are the same not withstanding the minor spigot differences on later JP's, TU4 and JP4S conrods are the same.

You don't need the larger clio TB, as its only a 1600.

[sammys]

Hi guys, thank you and sorry for my late answer....

my plan was a modified head, So first I wanted to disassemble the complete engine, use other camshafts, for example catcams, and facilitate + finely balancing the crankshaft, plan the head and facilitate the valve drive and flywheel. Polish the valves... The JP4s have no rocker arms like the 8V engines, so I thought on lighter hydraulic lifter and other springs.

Wide the intake ports and grind + deburr the intake system completely. Then use a Airbox and mapped the whole sytem, perhaps with a VEMS.

What do you think? Which catcams, springs and hydraulic lifter would you advise?

@welshpug/ Ross: I want wo use the stock pistons :) If the crankshafts are all the same, I could use a JP4 and buy a JP4S inlet manifold seperate? I would prefer a clio TB because its not electrical, I hate elektric tb's gas paddles and so on, like it if it's all analog ;)