What Head gasket ??

[stevepudney]

I've just had my rebuild bored out to suit some 87mm forged Wiseco pistons. I want to run 3 boost settings 1, 1.3 & 1.6 bar, but I would like to keep good low down torque of the standard motor.

If the new pistons are standard compression ratio what thickness metal head gasket should I use, and what size bore to suit the 87mm rebored block.

I'm guessing 1.2mm thick and 88mm bore. ????

 

[Nad]

Hmm I just hope my head gasket has a big enough bore now :lol: Go for 1.2mm, or if ur getting an aftermarket ECU u could try a 1mm.

Nad

 

[stevepudney]

Why the 1mm only if I'm getting an aftermarket ECU ??? Can the aftermarket ECU handle higher comp ratio then ??

And what bore size gasket did you get, ..........87mm?? Are you thinking thats to small now ??

 

[skiddusmarkus]

I don't know why but my 1mm Tomei one's bore is 88mm yet for 87mm pistons.The 1mm gasket raiess compression to approx 8.7:1(from 8.3:1) and could cause det hence the aftermarjet ECU to give better control over the mixture and timing.According to Nikko it should lower spoolup time by a few hundred rpm and give better torque/fuel consumption and off boost driveability.
I've got A Link ECU which will control my water injection,egt guage and soon a knock/lamda link so I'm not really worrried about det.

 

[campbellju]

Steve,
I very nearly bought the 1mm as well because of the extra free power and better "off boost" driveability. In the end I wimped out and went for standard HKS again because it will work and I was too worried about detontation.

To get it to work well, I figured I would need to run lower boost
(1.2bar max) to keep intake temperatures down and to be safe install a decent water injection system that kicks in when the car comes on boost. This is not my idea as its exactly what the rally pros do to have a very low lag 300bhp car.

Throwing a good chip in there would also solve the problem but by retarding the ignition timing when on boost. You would get less bhp per increase in boost realtivley speaking and effectivley a lower max power.

Fine if you're in the WRC and limited to 300bhp anyway.

To combat this you could always stick in a bigger turbo that runs lower boost and keeps your intake temps down to give you the higher power back but increases lag again.

At this point my head disappeared up my a**e and I went for standard 1.2mm HKS with my standard 87mm HKS pitons.

 

[skiddusmarkus]

I plan on running 1.8bar on high boost(not all time :shock: ),but I've taken measures to keep charge temps down.As well as WI,I've got FMIC,cold air box and bought a load of reflective material to wrap around the induction pipes-I might even use that stuff meant for the back of radiators too underneath.My exhaust manifold is also lagged to keep heat in.
The ECU won't necessarily retard the timing(although has the capability when inlet temps rise),but can get a more precise mixture and inject more fuel to cool things down if necessary.

 

[Nad]

I though rally cars didnt use water injection anymore, just like they also dont use water cooled brakes anymore. I am not going for water injection as I dont want the engine to rely on it. Yes u could say it is there for the safety margin but if i am paying 2.5k for an ECU I expect it to be able to cope without it.

I will also be getting the car mapped on super unleaded and then run it on optimax or other alternative as another safety measure.

Nad

 

[campbellju]

load of reflective material to wrap around the induction pipes-I might even use that stuff meant for the back of radiators too underneath.My exhaust manifold is also lagged to keep heat in.

Is that stuff any good? I've looked at it and IMO it seems a good idea but its expensive stuff for what it is. Ideally I want to run my turbo at 1.6bar so I'm also keen on keeping temps down.

 

[Nad]

I take it ur on about the reflective sticky back lagging. I had some and never buying it again. Lasted 2 days after the manifold cracked. I am just going to polish the whole induction side of the engine, and lag the whole exhaust side. On a cast manifold keeping the extra heat in the manifold shouldnt affect the manifold too much as it is thick, on other manifolds it can cause it to crack.

From what I have seen on the WRC cars they tend to make a whole shield that runs the length of the manifold so the heat is kept out of the engine bay but isnt held in the pipes themselves. The shields are large though as rally cars use long runners, for low down torque.

Nad

 

[campbellju]

I though rally cars didnt use water injection anymore, just like they also dont use water cooled brakes anymore. Nad

You're probably right, just saying its not my idea. 8)

BTW, have you got a 1mm head gasket on yours. The ECU might be able to cope with running the engine safely but the only way to stop detonation is by reducing charge pressure/temp or retarding the ignition. The ECU can only control one of those so all things being equal the engine must lose top end power.

It depends what sort of engine you and the next person are after. Personally I'm after one that works at the moment :lol:

 

[campbellju]

I take it ur on about the reflective sticky back laggingNad

Yeh, something like that. They do heat shields for turbo's as well which have been on my "Bottomless money pit" parts list but equally not likely to get purchased cos of price. The manifold lagging though just looks like some cheap heat protective material and yet costs about £100.

My other expectation is the lagging would stop cracking through reduced thermal shock, not the other way round :shock:

 

[skiddusmarkus]

I have some sheets of refelective material,It's a kind of fabric with foily stuff on one side.It's not sticky back.The stuff you put round back of radiators I was referring to was the foil on one side and bubble wrap on the other,not the stick on stuff.

The ECU might be able to cope with running the engine safely but the only way to stop detonation is by reducing charge pressure/temp or retarding the ignition. The ECU can only control one of those so all things being equal the engine must lose top end power.

The ECU Nad will use can do all 3.It can reduce boost,reduce temps by adjusting the mixture and retard the ignition as well.

 

[Nad]

My other expectation is the lagging would stop cracking through reduced thermal shock, not the other way round :shock:

Apparently it is because it holds the heat in the material rather than letting it escape.

Skid, I know what ur on about as I seen it in Demon Tweeks Motorsport mag. I just hope the ECU can do everything. Im not relying on water injection otherwise what happens when it runs out. Want my car to be as simple as possible, less to break that way!

Nad

 

[AJ4]

hey Nad, don't be so negative about WI, its no different from forgetting to check oil level or rad level

 

[memski]

Agreed, almost got rid of mine but am keeping it with the intention of using it to gain power rather than reliability this time round (and a large resevoir stored in the boot :lol: ).

 

[Nad]

hey Nad, don't be so negative about WI, its no different from forgetting to check oil level or rad level

Its more weight and just dont want to rely on it. If it shags up for a few seconds and ur engines been tuned on it, and I am talking high power engines here 400bhp+ its boom time.

Nad

 

[memski]

No different from your fuel system running lean for a few seconds then? Faulty line/pump, lean on a cylinder = boom. But hey, I'm being picky now, back on topic - get the 1mm hg

 

[Nad]

No different from your fuel system running lean for a few seconds then? Faulty line/pump, lean on a cylinder = boom. But hey, I'm being picky now, back on topic - get the 1mm hg

But the ECU will detect that and compensate. I dont know of an ECU that can tell when the water has run out and change maps

Right to clear this up, I was originally going to get the whole kit but after reading stuff over the internet decided against it. Everyone to their own. Its a bit like Nitrous oxide :lol:

Who knows in future I may change my mind, until that time when I am beaten by someone with it, I shall live without it.

Nad

 

[Keira]

its quite simple to keep an eye on water levels for W.I.

float switch on the resevoir and an led in the car and you can safely tell when its running low.

Not to sure when w.i. is actually needed but anything that helps to lower charge temps cant be a bad thing.