21 replies to this topic

[ropeman]

What sort of power should I expect from a standard 998 with a T2 (running around 10psi) and 12G295 head................75ish?

[Turbo Phil]

I would think this would certainly be achievable with that spec, if not a little more. Flywheel obviously.

Phil.

[ropeman]

Right back to the world of mini turbo's it is for me then

what are 1098's like over 998's for turboing? Does the little bit of extra tourqe make any difference?

[Wil_h]

I would have thought that turboing a 1098 over a 998 would produce slighty more torque, yes.

However, as a general rule of thumb a turbo motor usually make a similar torque to BHP, and 75lbft of torque would be good for a well modded 1275.

I also think that at 10psi you should make more like 80 to 90 BHP on a 998.

Wil

[ropeman]

My old 1330 turbo produced 108bhp with a massive 126lbft of tourque which I was pretty chuffed with.

Anyhow going back to the 998 idea does anyone have a good sugestion of camshaft? Also having never taken A+ 998 block to bits does anyone know whether the camshaft is a slot or a spider drive?

[Wil_h]

The camshafet can be any drive you like, just depends what oilpump you use. will be slot drive as standard.

Prefered cam is the KC500 (Kent) or an Mg metro (non-turbo), they are the same cam.

This is my experiance only, I don't know another running 998 turbo. But I tried an Avonbar PH2 and it didn't work for me.

Wil

[ropeman]

Slot drive is good! Means I can cheat (be lazzy) and do a cam change with the engine in situ. Oh the small engine turbo route seams more and more like a good idea

Cam wise I want something quite lumpy as the car wont be a daily drive so I can get away with something a little more wild Or do turbo engines not suit particularly wild cams?

[Wil_h]

You are right, turbo engines do not suit wild cams. A com with a big overlap will move the boost threshold higher up the rev range, which is the last hing you want.

My 998 turbo has 140bhp with a KC500, so what more do you need. I've kept the same cam and am hoping for 150+ with the new engine.

What are the pistons you have then? if it's the later slipper type pistons then make sure you keep the boost to a maximum of 10psi. If you have the earlier circlip fitment pistons (P20773 type) then these will take much more punnishment.

Wil

[ropeman]

Point taken, KC500 it is then.

I have the earlier type pistons! Yay! That was more of a luck thing, I had no idea so cheers for the info.

[Turbo Phil]

This topic seems to be popping up on a regular basis now.

Will, would you be wiling to post up a rough spec of yours + power output etc, & any other pitfalls to watch for such as the piston advice above.
I've never Turbo'd a 998 or a naturally asp motor for that matter so you certainly have a better knowledge in this area of what's suitable.
I could then pin this for future reference.

Phil.

[Wil_h]

I'm sure I could knock something up. Bit busy atm building the car. But once it's finished I'll write up the njew spec and put in a few nuggets of info that I've picked up along the way.

Wil

[Turbo Phil]

Cheers mate !

[Pavel]

RIght here's Will's old spec. Not sure how it changed since then but it should still give a pretty good idea. Will if for any reason you don't want people to see it, PM one of the mods and they'll delete my post.

TURBO SYSTEM

MG Metro Turbo System – Inlet & exhaust manifolds, Garrett T3, Alloy Plenum, Carburettor;
Fuel Pump - 60psi roller vane Sytec pump;
Intercooler - Isuzu Trooper Intercooler with various Silicon hoses;
Dumpvalve - Plunger type, mounted on inlet to plenum;
Exhaust - Maniflow turbo downpipe connected to bespoke 2” system.

ENGINE

Cylinder Head - 12G940 with ground out chambers to lower CR (7.3:1) and sodium filled exhaust valves;
Block - Pocketed to allow fitment of 12G940, centre main strap;
Pistons - Crappo hepolite type with 7cc dish;
Con Rods - Standard A+;
Crank - Balanced, wedged and nitrided;
Camshaft - Kent 500 with 1.5 roller rockers and Beltdrive.

DRIVETRAIN

Flywheel & Clutch - Ultralight Minispares Flywheel and backplate, gray diaphragm and sintered paddle clutch plate;
Drop Gears - Straight-cut (1.0416:1);
Gearbox - Straight Cut Close Ratio (Minispares set)
Diff - Tranx LSD (This is a new mod, used cross pin open diff till now).






COOLING

Radiator - Standard 3 core (could do with something bigger/better);
Water Pump - Standard pump filed to allow head fitment;
Fan - 4 blade metal fan.

IGNITION

Fully mappble Megasquirt system.

POWER and PERFORMANCE

120-130bhp @ 6100rpm and 18psi;
120 ftlb torque at 4900rpm;

Boost threshold around 4000rpm.

Standing ¼ mile in 14.08 seconds at 96mph.

0 to 60 in 5.5 seconds (approx).

[Asphalt]

130bhp out of an 998!?
Am I understanding you right!?

Do you have any rolling-road data-sheets/diagrams to proof this!?
Sorry, but i can`t believe it...

best regards,
Jan

[Wil_h]

140 mate. And the new engine (to be rollered next week) is a vast improvement, expect 150+. My car does 14.0 1/4 mile times, so it's no BS