TRD Thinner Head Gasket

[5T4R7ET N/A]

Hi,

I belive that the standard head gasket of a N/A is 0.8 mm thick. I have seen a TRD headgasket for the 4efe which is 0.6mm thick. You can see where is going.

I will have the following supporting engine mods before the gasket goes on.

1. HT Leads

2. Air Induction Kit

3. 2 Inch Cat Back System with No Middle Box.

4. Corolla Inlet Mani

5. And possible OBX Manifold

Ive probably missed some things.

I know that the thinner gasket will raise my compression ratio. But what will the benefits of it be. BHP/Torque wise. Estimate with and without OBX as its not a defo at the mo.

Lastly do i need to make any additional mods for the TRD Gasket to be fitted?

Thanks

[ste91]

I've been looking into this myself and am quite interested to see what results you get with it.

I think higher octane fuel may be needed to stop it from detting with the higher compression, not sure though.

[5T4R7ET N/A]

So, anyone else have any thoughts on this?

[Jozinobi]

You can get a 0.5mm trd head gasket as well because I have one waiting to go on.The raise in compression will be fairly small. I have no means to measure the compression ratio rise as I dont have the skills but a decent engine specialist or mechanic will be able to calculate this for you.

There is no accurate way to measure or predict what benefits or drawbacks you are going to have from fitting one, the same goes for the obx. Im the only one known in the UK to fit an obx to my 4EFE and it wasnt great, it is designed for the 5EFE after all. The 4E lacks torque and it will find it hard to make much more without extensive headwork geared towards extra torque which will still be minimal. There needs to be more na owners attempting these tuning options before more accurate info can be given. The only way to measure gains before and after adding modifications are the rolling road and dyno. There is no correct option, if you have the budget and inspiration try some things for yourself.

[Toby@ToyTuning.com]

As above it will raise the CR a little, it also depends if you skim the head or modify the combustion chamber as this will also effect CR. We use TRD gaskets with some of our lower power forged engine rebuilds as we use lower CR dished pistons (10cc drop per piston). If the customer is using one of our Hybrid CT9's and still wants to retain good engine response then we use a TRD thinner gasket to counteract the lower CR of the pistons otherwise the CR is too low.

At the opposite end if the customer wants a 300hp monster we use the same pistons and a 1.2-16mm gasket to lower the CR for big boost, avoiding det and aiding reliability in the long run. Some companies use stock CR pistons and crazy thick gaskets like 2.4-3.0mm but we don't like this practice. Raising the CR will aid engine reponse in general but as above you need to watch for det as too high and you will see problems. Lot's of drag cars run mad CR's like 11:1 with turbos using very high octane race fuel (115RON and above) but in the real world we can only really get 98-99RON so we tend to run lower CR's.

Hope this helps.

Toby

[ste91]

How hard is it to change a head gasket? Could someone with fairly decent mechanical knowledge do it themselves or would a proper mechanic need to do it?

From what I can see, the TRD headgaskets aren't that expensive in comparison to some other mods, and even if it's a small increase - every little helps.

[Toby@ToyTuning.com]

Yeah it's not that hard, I use Kevin to do all our mechanical work like this but it's not the actual fitting of the parts and refitting that is the hard bit, it's making sure the block and head are perfectly flat to ensure the best possible seal. Quite a few of our customers do these themselves so it can be done but if it all unsure then best to get someone to do it

T

[Asad]

Aslong as you get the head skimmed by some1 who knows what they are doing + prepare and clean the bottom block up properly its ok.

Getting a head skimmed, chemicaly cleaned, crack tested etc can cost around £150+