Need some help.

[airhead04]

Ok, my stepfather and I were talking today about what size mhg to put on my engine today. He thinks that it doesnt effect compression or cause detonation, so he wants to put a 1.2mm mhg. Well I, for obvious reasons dont want to put a 1.2 mhg. The block and head have been resurfaced before. Ill be putting forged pistons in, so they can withstand detonation a little better but, I dont think they will last very long.

So can someone give me a link that shows whats the causes of putiing the incorrect mhg on. Please dont direct me to a forum or a bhg thread or something. Im talking about a link thats from a company that has researched it.

And yes I read the mhg sizing thread IJ created.

 

[IJ.]

Measure the block and head.

 

[lewis15498]

Companies dont research that shit, they already know what happens.
I'm assuming its your car and your dime. Why does what your stepfather has to say have anything to do with it.
If its his car, let him do what he wants. If he wont listen to reason, hes gonna have to learn the hard way.
In addition to increasing the compression ratio, without adjustable cam gears its gonna alter the valve timing as well. Its pretty safe to assume your not going to run stock boost, or you wouldnt be messing around with MHGs and forged pistons. If you do this then crank the boost your likely going to have problems.

 

[airhead04]

Measure the block and head.

I know that IJ, I read your thread.

I let my stepdad order the parts, and he wants to order a 1.2 mhg. And thats thinner than stock. So it may cause detonation. I just need proof that it causes this, to show to my stepfather.

 

[Guyana00]

This is ridiculous, you have to prove it to him? He doesn't understand how compression ratios work?

I think you should just call toyota and ask them if different heasgasket thicknesses make a difference and let him listen in.

 

[lewis15498]

This is ridiculous, you have to prove it to him? He doesn't understand how compression ratios work?

I think you should just call toyota and ask them if different heasgasket thicknesses make a difference and let him listen in.

IDK about your area but around here, chances of getting someone from the toyota dealership that actually knows what they are talking about on the phone is pretty slim.

 

[airhead04]

I gave him the money to buy the parts. He gets the better deals then me. BUT he also is helping me with the moola as well. I just want him to understand the ccause and effect of the size of head gaskets. thats all.

 

[hvyman]

the stock hg is 1.37 compressed and you have taken material off both the head and block. that amount that has been taken off is supposed to be added to the stock hg thickness to compensate the amount of material that in no longer there.

almost anytime you use a 1.2mm hg the comp ratio is going to go up. i would venture into a guess that you would most likely need a 1.5mm-2.0mm hg.

if you have a stock hg laying around measure it. the more material you remove from the head the closer the valves sit towards the engine. if you remove soo much and not compensate with a thicker hg you will not be able to set the cam/ crank timing and then engine will never run properly.

im guess your dad is a old skool ford chevy kinda guy where you can almost take as much off the heads as you want(to a certain degree) and the cam crank timing will be fine because the cam and crank never moved.

with over head cams as you machine the head the cams come closer to the pistons and eventually will result in mega problems.

 

[Guyana00]

http://www.turbobygarrett.com/turbobygarrett/tech_center/faqs.html

14.How do I adjust my compression ratio?
The easiest and most effective way to accomplish this is through the use of either higher/lower compression pistons, and/or using a head gasket of a different thickness.