Which Head Gasket

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Paul R
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Which Head Gasket

Post by Paul R »

Hi,

I'm wondering which head gasket to go for? My car has a rev1 engine(block and head) and It will be running with a rev3 manifold and Ct20 turbo with de-cat pipe. I'm planning on running about 1bar.

So - which head gasket should I go for? Anyone got prices and places to get one from? I dont want to alter the cmpression ratio if I can help it.

Cheers,

Paul.
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Re: Which Head Gasket

Post by gtschris.com »

Paul R wrote:Hi,

I'm wondering which head gasket to go for? My car has a rev1 engine(block and head) and It will be running with a rev3 manifold and Ct20 turbo with de-cat pipe. I'm planning on running about 1bar.

So - which head gasket should I go for? Anyone got prices and places to get one from? I dont want to alter the cmpression ratio if I can help it.

Cheers,

Paul.


Paul,

to keep compression ratio the same you want a 1.0mm multi steal layer gasket.

I sell cosmetic MSL gaskets and will have 1.0mm in stock soon.

You can use a Toyota rev3 gasket but you need to drill a couple of hole in it (which my personal feel is this is not a very good idea).

PS- the 8 stud rev3 exhaust manifold will not fir your rev1 7 stud head, but the ct20b bolts right upto the rev1 exhaust manifold.


regards,

chris
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Paul R
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Re: Which Head Gasket

Post by Paul R »

gtschris.com wrote:
Paul R wrote:Hi,

I'm wondering which head gasket to go for? My car has a rev1 engine(block and head) and It will be running with a rev3 manifold and Ct20 turbo with de-cat pipe. I'm planning on running about 1bar.

So - which head gasket should I go for? Anyone got prices and places to get one from? I dont want to alter the cmpression ratio if I can help it.

Cheers,

Paul.


Paul,

to keep compression ratio the same you want a 1.0mm multi steal layer gasket.

I sell cosmetic MSL gaskets and will have 1.0mm in stock soon.

You can use a Toyota rev3 gasket but you need to drill a couple of hole in it (which my personal feel is this is not a very good idea).

PS- the 8 stud rev3 exhaust manifold will not fir your rev1 7 stud head, but the ct20b bolts right upto the rev1 exhaust manifold.


regards,

chris


Ok, cheers.

What difference would I see if I fitted a 1.1mm gasket and is it a good idea??

When you saythat a rev3 manifold wont fit a rev1 head, do you mean it wont seal properly or what?

I have a rev3 manifold on my car already! as far as I can see, the rev3 manifold just has two extra stud holes - that arent used on my car, appart from that, they are the same??

Cheers,

Paul.
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Re: Which Head Gasket

Post by Owen @ Kent Car Craft »

GTSchris can supply good Cometic 1.4mm gaskets
You wouldn't notice the comp. ratio change 'that much' when driving it and it would save having to change it or lower the chances of Det. when you dicide to tune it later on.

Thick HG = Insurance for Pistons when they cost £400 a set.
just my 2p
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Re: Which Head Gasket

Post by gtschris.com »

Paul R wrote:
gtschris.com wrote:
Paul R wrote:Hi,

I'm wondering which head gasket to go for? My car has a rev1 engine(block and head) and It will be running with a rev3 manifold and Ct20 turbo with de-cat pipe. I'm planning on running about 1bar.

So - which head gasket should I go for? Anyone got prices and places to get one from? I dont want to alter the cmpression ratio if I can help it.

Cheers,

Paul.


Paul,

to keep compression ratio the same you want a 1.0mm multi steal layer gasket.

I sell cosmetic MSL gaskets and will have 1.0mm in stock soon.

You can use a Toyota rev3 gasket but you need to drill a couple of hole in it (which my personal feel is this is not a very good idea).

PS- the 8 stud rev3 exhaust manifold will not fir your rev1 7 stud head, but the ct20b bolts right upto the rev1 exhaust manifold.


regards,

chris


Ok, cheers.

What difference would I see if I fitted a 1.1mm gasket and is it a good idea??

When you saythat a rev3 manifold wont fit a rev1 head, do you mean it wont seal properly or what?

I have a rev3 manifold on my car already! as far as I can see, the rev3 manifold just has two extra stud holes - that arent used on my car, appart from that, they are the same??

Cheers,

Paul.


if its got 2 extra stud holes unused it be a rev2 manifold, the port are in the same play rev1/2 but rev3 posts are diffrent shape and position thus a 8 stud rev3 manifold will not go on a rev1/2
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Paul R
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Re: Which Head Gasket

Post by Paul R »

gtschris.com wrote:
Paul R wrote:
gtschris.com wrote:

Paul,

to keep compression ratio the same you want a 1.0mm multi steal layer gasket.

I sell cosmetic MSL gaskets and will have 1.0mm in stock soon.

You can use a Toyota rev3 gasket but you need to drill a couple of hole in it (which my personal feel is this is not a very good idea).

PS- the 8 stud rev3 exhaust manifold will not fir your rev1 7 stud head, but the ct20b bolts right upto the rev1 exhaust manifold.


regards,

chris


Ok, cheers.

What difference would I see if I fitted a 1.1mm gasket and is it a good idea??

When you saythat a rev3 manifold wont fit a rev1 head, do you mean it wont seal properly or what?

I have a rev3 manifold on my car already! as far as I can see, the rev3 manifold just has two extra stud holes - that arent used on my car, appart from that, they are the same??

Cheers,

Paul.


if its got 2 extra stud holes unused it be a rev2 manifold, the port are in the same play rev1/2 but rev3 posts are diffrent shape and position thus a 8 stud rev3 manifold will not go on a rev1/2


right, Yes, this makes sense now!! Your right, it is a rev2 manifold on my rev1 head at the moment (I was told otherwise before).

I've double checked what I am actually getting to replace my current manifold. It's a rev1 manifold with a CT20 turbo on it.

Cheers Chris.

Paul.
Paul R
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Re: Which Head Gasket

Post by Paul R »

Elmo Owen wrote:GTSchris can supply good Cometic 1.4mm gaskets
You wouldn't notice the comp. ratio change 'that much' when driving it and it would save having to change it or lower the chances of Det. when you dicide to tune it later on.

Thick HG = Insurance for Pistons when they cost £400 a set.
just my 2p


hmm...! Is there no down side to fitting a thicker head gasket? Has any one else had any experience of this?

Cheers,

Paul.
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BenF
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Re: Which Head Gasket

Post by BenF »

Paul R wrote:
Elmo Owen wrote:GTSchris can supply good Cometic 1.4mm gaskets
You wouldn't notice the comp. ratio change 'that much' when driving it and it would save having to change it or lower the chances of Det. when you dicide to tune it later on.

Thick HG = Insurance for Pistons when they cost £400 a set.
just my 2p


hmm...! Is there no down side to fitting a thicker head gasket? Has any one else had any experience of this?


Yes, I've got a HKS 1.6mm stopper HG on my Rev2 - I wanted to fit a TRD 1.4mm one but Fensport were unhelpful and couldn't give me a firm delivery time and date when i was doing my rebuild.

Net effect of lower CR is a reduction in fuel economy, but improved resistance to detonation

NB The 'proper' way to reduce compression ratios is to fit new pistons though ..
Paul R
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Re: Which Head Gasket

Post by Paul R »

So a 1.1mm head gasket would be a fair bet then ??

Reduce detonation slightly with hardly any loss in fuel economy?

Cheers,

Paul.
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Re: Which Head Gasket

Post by MR2Mania »

ISTR that the stock Rev1/2 HG is about 1.1-1.2mm? I know for sure that the stock Rev3 one is 1.05mm uncompressed, 1.0mm compressed.

Changing the CR with a thicker HG is WRONG! Sorry, but it affects your squish (what goes on in your combustion chambers as the charge is compressed before ignition). The only proper way to change CR is to make changes to the combustion chambers and different piston crown design, IMHO.

For a Rev1/2, one of the best AFFORDABLE gaskets is a TTE 1.2mm version, although they're not that easy to get hold of.
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Re: Which Head Gasket

Post by gtschris.com »

MR2Mania wrote:ISTR that the stock Rev1/2 HG is about 1.1-1.2mm? I know for sure that the stock Rev3 one is 1.05mm uncompressed, 1.0mm compressed.

Changing the CR with a thicker HG is WRONG! Sorry, but it affects your squish (what goes on in your combustion chambers as the charge is compressed before ignition). The only proper way to change CR is to make changes to the combustion chambers and different piston crown design, IMHO.

For a Rev1/2, one of the best AFFORDABLE gaskets is a TTE 1.2mm version, although they're not that easy to get hold of.


I would have to disagree with mr2mania, droping the c/r on a rev1/2 with a thicker h/g is good news. The rev1/2 runs a fairly high compression ratio of 8.8:1 from the factory (t3 cosworths run 8.0:1 stock) that coupled with a JDM ecu mapped for high octane jap fuel + a factory intercooler that heat soak at low speeds = prime candidate for detonation problems, anything you can do to help avoid detonation is a bonus when running above standard boost levels.

I agree with mr2mania in the respect that the best solution is a built engine to achive your target c/r. That said not everyone requires a built engine for there target BHP.

I have had nothing but good feedback regarding the quality of cosmetic head gaskets and run a 1.9mm one myself, £90 for a 1.4mm high quality multi layer steal gasket in my opinion offers genuine valve & a c/r of 8.5:1 (the same as a factory rev3).
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Re: Which Head Gasket

Post by gtschris.com »

Paul R wrote:So a 1.1mm head gasket would be a fair bet then ??

Reduce detonation slightly with hardly any loss in fuel economy?

Cheers,

Paul.


i look to drop it to 8.5:1 (same as a stock rev3) this needs a 1.4mm

a 1.1mm would merely net you 0.075 drop to 8:725:1 not worth the bother.
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Re: Which Head Gasket

Post by MR2Mania »

gtschris.com wrote:I would have to disagree with mr2mania, droping the c/r on a rev1/2 with a thicker h/g is good news. The rev1/2 runs a fairly high compression ratio of 8.8:1 from the factory (t3 cosworths run 8.0:1 stock) that coupled with a JDM ecu mapped for high octane jap fuel + a factory intercooler that heat soak at low speeds = prime candidate for detonation problems, anything you can do to help avoid detonation is a bonus when running above standard boost levels.


That's your prerogative to disagree mate, but let me throw a few facts your way:

* Why is BenF's now less economical off boost, etc, since his thicker HG? Maybe his VE has been reduced, or that combustion is not as complete as before? ;)
* Evos have 8.8:1 CR as standard, and yet you still hear of them running 2bar plus of boost. And they spool pretty well!
* Low CRs is an old Cosworth line of thinking. How many other tuned 2 litre turbos run low CRs? Again, look at what some of the Evo boys are achieving, some with RAISED CRs, and then come tell me that dropping the CR is the way to go. Or look at what other top Jap tuners are doing. You'll actually find it difficult to get a straight answer from most top tuners when you ask them what the CR is, because they don't want you to know that they've actually raised the CR.

Do you actually know what squish is, and how a thicker HG can affect it?

Incidentally, I've RAISED the CR on my own Rev3 build, and I'm glad I did. :D
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Re: Which Head Gasket

Post by MR2Mania »

GTSCHris, let me explain why I think that it's a bad thing to change the CR with just a HG. After all, I'm looking at the bigger picture.

Let's say you've got a Rev1/2, and want to get more power from it, but from standard internals. Chances are, you're going to be getting a bigger turbo, right? Ok, let's say you've got a hybrid CT26 on, as has BenF. You then decide to lower the CR so that you can run most boost without det. But, at the end of the day, if the engine is stock, you still won't run higher than 1.4bar, because your pistons WILL crack their ring lands if you run more boost. We've seen that Rev3s have no issue running 1.3-1.4bar boost on the stock ECU (if you raise the Fuel Cut point), and I also used to run 1.3bar on my Rev1, although only in the midrange. I didn't suffer det on either my Rev3 or Rev1, and in fact the Unichip made sure that I was getting the best from my package.

OK, back to the scenario. For the same given boost, with a lower CR your cylinder pressures are less (because of the CR drop - remember, the CR magnifies the boost being induced), so VE is down too. But does it make it less prone to det? For the expense and hassle of replacing the HG, would you not be better off getting a better IC (chargecooler would be best), so that you reduce the chance of det this way? Also, by improving the IC's efficiency, you're probably making a bigger improvement in performance than you would be with a bigger turbo alone. A better IC is a must way before any new turbo, IMHO. Also, you would not need to lower CR, your VE would stay the same (and as intended by Toyota, who let's not forget developed this engine from the race proven 503E, and further developed the 3SGTE in rallying!).

Do you see my point, now? The changed IC would yield a better improvement than just changing the HG. With a thicker HG, you're forced to run more boost to compensate for what you lose by reducing the VE, and that's not even taking into account how less efficient your combustion is because the mixture hasn't been squished properly.

Don't get me wrong, I think the Rev1/2 HG needs to be replaced with a decent metal one if you're going to be running more boost reliably, but there are also other areas of the engine that you should be concerned about at the same time. I certainly wouldn't lower the CR with a HG.
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Re: Which Head Gasket

Post by gtschris.com »

MR2Mania wrote:
gtschris.com wrote:I would have to disagree with mr2mania, droping the c/r on a rev1/2 with a thicker h/g is good news. The rev1/2 runs a fairly high compression ratio of 8.8:1 from the factory (t3 cosworths run 8.0:1 stock) that coupled with a JDM ecu mapped for high octane jap fuel + a factory intercooler that heat soak at low speeds = prime candidate for detonation problems, anything you can do to help avoid detonation is a bonus when running above standard boost levels.


That's your prerogative to disagree mate, but let me throw a few facts your way:

* Why is BenF's now less economical off boost, etc, since his thicker HG? Maybe his VE has been reduced, or that combustion is not as complete as before? ;)
* Evos have 8.8:1 CR as standard, and yet you still hear of them running 2bar plus of boost. And they spool pretty well!
* Low CRs is an old Cosworth line of thinking. How many other tuned 2 litre turbos run low CRs? Again, look at what some of the Evo boys are achieving, some with RAISED CRs, and then come tell me that dropping the CR is the way to go. Or look at what other top Jap tuners are doing. You'll actually find it difficult to get a straight answer from most top tuners when you ask them what the CR is, because they don't want you to know that they've actually raised the CR.

Do you actually know what squish is, and how a thicker HG can affect it?

Incidentally, I've RAISED the CR on my own Rev3 build, and I'm glad I did. :D


I am reading a great book at the moment (maximum boost by cork bell) I found a paragraph that sums it up….

“What is the best compression ratio for a turbocharged engine?
There is no such thing as the best or ideal compression ratio. The simple fundaments are:

The lower the compression ratio, the easier it is to produce a lot of boost with no detonation.

The higher the compression ratio, the greater the fuel efficiently and non-boosted response.”

Ben is running the same 1.6mm head gasket I ran a while back, I can’t comment on drop in fuel efficiently to be honest as I never have used my gts for commuting /everyday use – its just a weekend toy for road/track racing etc. My practical experience of the 1.6mm was no detonation probs and no adverse increase in EGT, my experience was a good one therefore I would be happy to recommend it, this is not to say it am correct or it is suitable for every tuned MR2 in the country.

I am not going too disagreed with the proven facts behind squish / quench area, from what I have read 0.04” or 0.1mm is the max you want. The 3sgte has far more than this standard as you have the head gasket + deck height.

Just out of interest do you know if the rev3 has the same deck height as a rev1/2 (I never measured it).

Rev3 has 1.2mm head gasket standard (0.2mm more than rev1/2) so that combined with same deck height would mean a rev3 has a larger squish volume?
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Re: Which Head Gasket

Post by gtschris.com »

MR2Mania wrote:
gtschris.com wrote:I would have to disagree with mr2mania, droping the c/r on a rev1/2 with a thicker h/g is good news. The rev1/2 runs a fairly high compression ratio of 8.8:1 from the factory (t3 cosworths run 8.0:1 stock) that coupled with a JDM ecu mapped for high octane jap fuel + a factory intercooler that heat soak at low speeds = prime candidate for detonation problems, anything you can do to help avoid detonation is a bonus when running above standard boost levels.


That's your prerogative to disagree mate, but let me throw a few facts your way:

* Why is BenF's now less economical off boost, etc, since his thicker HG? Maybe his VE has been reduced, or that combustion is not as complete as before? ;)
* Evos have 8.8:1 CR as standard, and yet you still hear of them running 2bar plus of boost. And they spool pretty well!
* Low CRs is an old Cosworth line of thinking. How many other tuned 2 litre turbos run low CRs? Again, look at what some of the Evo boys are achieving, some with RAISED CRs, and then come tell me that dropping the CR is the way to go. Or look at what other top Jap tuners are doing. You'll actually find it difficult to get a straight answer from most top tuners when you ask them what the CR is, because they don't want you to know that they've actually raised the CR.

Do you actually know what squish is, and how a thicker HG can affect it?

Incidentally, I've RAISED the CR on my own Rev3 build, and I'm glad I did. :D


Hey, Dino never realise it was you till I check out your website :) didn’t know web development was your career, thought you work for Owens Development ? (nice site by the way)

Anyways…………

I agree I would definitely go with a uprated side mount intercooler and / or water injection before big turbos etc, I have always appreciated the importance of intercooling but it wasn’t until I looked into ideal gas law etc a few years back I realised the physics behind intake charge density.

Despite retailing a range of MLS head gaskets I would never recommend a owner to pull there cylinder head for the sake of it, but if its off anyway or a leak down/compression test has identified a problem with the h/g I would recommend a replacement MLS.
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Re: Which Head Gasket

Post by Jimbob »

Looking at piston comp ratios and HG thicknesses its soooo confusing.

Considering JE seem to be a decent manufacturer of pistons but generally have a high CR. Would it be an idea if using Higher CR pistons to then use a Thicker HG to lower it again?

I have to say I thought the thinner any gasket the better in a pure engineering sense. Although HG's open up a whole new ballgame.

Can anyone tell me the standard CR of a Rev2? I would like to get slightly lower CR pistons, and keep the HG the same if possible, or use a slightly thicker HG if worst somes to worst

Cheers
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Re: Which Head Gasket

Post by gtschris.com »

Jimbob wrote:Looking at piston comp ratios and HG thicknesses its soooo confusing.

Considering JE seem to be a decent manufacturer of pistons but generally have a high CR. Would it be an idea if using Higher CR pistons to then use a Thicker HG to lower it again?

I have to say I thought the thinner any gasket the better in a pure engineering sense. Although HG's open up a whole new ballgame.

Can anyone tell me the standard CR of a Rev2? I would like to get slightly lower CR pistons, and keep the HG the same if possible, or use a slightly thicker HG if worst somes to worst

Cheers


"Can anyone tell me the standard CR of a Rev2" 8.8:1 & rev3 is 8.5:1
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Re: Which Head Gasket

Post by V8Killer »

gtschris.com wrote:

I am reading a great book at the moment (maximum boost by cork bell) I found a paragraph that sums it up….



I've borrowed that book from my local uni library. Its a dated book and is in serious need to be updated. Times have moved on.

Am sure this is the same book that said Water Injection is just a band aid...LOL!
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Re: Which Head Gasket

Post by paul port »

Chris,
Are these gaskets available in thicknesses below 1mm?

The reason I ask...
Some USA 'off the shelf' pistons come in fairly low CR's EG, Arias - designed to give a 8.5CR on a Rev1/2, so if used on a Rev3, the ratio will end up even lower - especially if any material has been removed from the combustion chambers during head work.

Seeing as these pistons are usually designed to be compatible with over-size valves, could the resulting CR be raised slightly again by using a thinner gasket without worrying about valve clearance.

Thoughts Chris / Dino??

As an example, Dino, What was your resultant CR compared to what the piston manufacturer suggested for a R1/2 engine?

Paul
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