Toyota Celica Supra Forum banner

1 - 20 of 89 Posts

·
Registered
Joined
·
312 Posts
Discussion Starter #1
Hey all.

I just want to show some picture of my new engine that i am building this winter.
This is the description so far...

7mge 24V head.
5mge pistons modified for 24v head.
6mge short block.
Itb´s from BMW M3 3.2.

The engine will be mounted with new bearings, rings, metal head gasket, and new gaskets.
I have got 296 degrees cams for the project, and also i have to make 2 adjustable cam gears.
The exhaust header is fro OBX, and made of stainless steel.

Here is some pic...more to come.







The modified piston so i can raise the comp. ratio...



More will come later... :)

best regards Jens Pedersen
 

·
Registered
Joined
·
4,517 Posts
That is excellent, Jens! I am really looking forward to seeing all of this in your car...
 

·
Registered
Joined
·
606 Posts
Den er bare sexy den motor Jens..... Kan den passe i min....??????????????????????
Es wurd eín specialitet werden dass niemann früher gesehen hat.
Teasing you.
I come an watch that wonder Jens.... call me when it ready to start..
 

·
Registered
Joined
·
312 Posts
Discussion Starter #6
He he....you are så meget Wilkommen Herr Hans ;-).

The flywheel on this engine will be this.....also homemade.

It is tested on my other engine and works very good !








Incl clutch the weight is 8.6 kg, and the original is 17kg :).
 

·
Registered
Joined
·
312 Posts
Discussion Starter #7
Hey again.

Here is some pic, where you can see the difference from the 7mge piston to the 5mge (high compr) piston after some modification..
Also i got the new ring set mounted here, so tomorrow i will mount the pistons to the rod and perhaps also mount them in the block :)







Best regards Jens Pedersen
 

·
Registered
Joined
·
1,089 Posts
Ummmm ... what's your final compression ratio going to be?

Taking a high compression 5m Piston and machining four more valve reliefs ... is going to lower your compression substantially.

You made a piston that is relieved for 6 valves, but only uses four of them. The extra two, lower your compression without any need to have them.

That flywheel is bitching .... but still scares the hell out of me.

nice work.
 

·
Registered
Joined
·
3,963 Posts
You made a piston that is relieved for 6 valves, but only uses four of them. The extra two, lower your compression without any need to have them.
yeah, and all those sharp edges are not a good thing either. considering the piston works in harmony with the combustion chamber, hell, it's the bottom half of the combustion chamber. I've circled about the worst thing you could ever do with regards to piston design. sharp points = Localized hot spots = pinging, especially with high compression. you've also significantly reduced the head-squish band area around the outside of the piston with your large cutouts. This is also bad for performance in many ways. now, I've only done some light reading on piston and combustion chamber design, but if you've gone this far I'd highly suggest buying some new, properly made ones. I see nothing positive about the ones you've made.... Jens, I'm sorry for being so critical considering you seem to know what you're doing with regards to most things, but you definitely need to re-examine this area of the engine. It may work in pratice but from just looking at them, they don't look like a good solution.

 

·
Registered
Joined
·
1,089 Posts
Steve, I was thinking the same thing ... but figured they'd melt round fairly quickly.:laugh:

But seriously now ...

If you machined the sharp bits off on of the pistons (removing more material, lowing compression even lower) and do a final combustion chamber volume check for compression calculations I fear you will be very dissapointed.

A motor with this much machine work put into it NEEDS the correct pistons. (Or a big frick'in turbo ... on low comps.)
 

·
Registered
Joined
·
2,244 Posts
y not just get custom pistons that can handle high power? would be helluva lot less work...

and i agree with the flywheel being scary part...id be seriously scared for my legs...
 

·
Registered
Joined
·
4,871 Posts
Steve is right! I hate to say this, but those custom machined 5M pistons are going to cause you nothing but grief if you decide to use them. Steve has spelled out all of the dangers very well. The crown thickness is also bound to be rather thin where you've cut the new valve reliefs. I would also wager that if you were to measure the crown volume of both pistons that the 7M piston will actually yield a lower volume and be the higher comp. piston of the two. There's bound to be some high comp. 7M pistons available that are much more suitable.

The flywheel is an excellent piece of fine workmanship, but it scares the he-- out of me too. The bare aluminum friction surface is definitely not going to hold up. If you let the aluminum surface get scored and chewed up and overheated from friction, some very bad things could happen.



Just my honest 2 cents worth that I hope you will carefully consider!
 

·
Super Moderator
Joined
·
10,546 Posts
I want to comment on your choice of the 6m crank and rods too but everyones picking on you right now so I'll leave it be for now lol. I think I said all I needed to say about that in your other thread anyways

BMW ITBs on a 7m head though, mega cool. Looking forward to this build, which car is this for though? I thought you said you were going to finish the car that the other motor was in next? ;)
 

·
Registered
Joined
·
312 Posts
Discussion Starter #15
Hey all.
I dont care that everebody is picking on me :).
I can handle it!

First of all.
The flywheel is tested at my other engine and works very fine.
The flywheel is made of a special type of steel that is used for that kind of things.
I work at a place where we build machines , as we also are building flywheels for so please trust me.....the biggest flywheel we are making is 1400mm in diameter!!
I know what i am doing!

The dyno numbers on my other thread is with the flywheel installed.
The clutch is a tilton clutch, not one i made by my self, and it is good for 950+nm.
There is a lot of rally cars and other hard used engines that are using this type of clutch.

The piston i use for this project will give the engine a HIGHER compression ratio.
And as you TIRESHREDDER drawed at the picture :).....those sharp edges will be removed before mounting.

If i do the plasticine test the 7m piston dry weight is 404g
Filled with plasticine to the top the weight is 422g
Difference 18g

The 5m piston is dry 363g
Filled with plasticine 374g
Difference 11g

So between 7m std piston and my custom made 5m piston there is a difference at 7g.
And then the dome at the 5m piston as i also found the weight of.
The value for that is 4g.

So 11g is the total difference.
1g is 0.001 kg.

I also did the test with water and 1g water is 1ccm.

So With the 5m piston i raise the compression with 11ccm.

It will be about 11.2 in compression!

The guy who helps me with this , has build many other engines like this.
Not toyota but opel!
He got his own firm and he is living of building race engines.

I do things many people only are talking about, and even some things that havent been said yet :).
I know that there is a big risk when i am re-designing the original parts, but i am willing to take that risk.
I will buy some custom made pistons one day, 85mm special build for this project, but i also want the rods to, so that is close to 5000usd just for that.
So i hope this engine can be able to run until i have collected 5000usd :)

Then it would be 3.2 24V :)

Thanks for all this critical conversation, i like to hear your oppinion for this project :).

At this pics you see 2 of my 3 little helpers he he he ....

They better learn from the beginning, what it is all about ;-)

Best regards Jens Pedersen







 

·
Registered
Joined
·
1,089 Posts
Great! Now those numbers are looking good.

Even with a few cc's removed to clean up the sharp edges you could easily be in the 10:1 area. If you want higher ... skim the head.

I still think you need to remove the boundries that seperate the valve pockets for proper flame propgation and reduced pinging/hot spots.

Keep in mind ... this is all CONSTRUCTIVE critisism. We all want to hear/see this motor work.
 

·
Super Moderator
Joined
·
10,546 Posts
When you buy the rods and pistons, you should switch to a 5m crank too. That is the most expensive part about building a 5m\7m hybrid is that the 5m rods are pretty weak compared to 7mgte rods. I think the .2 liters of displacment you loose will be more then made up by being able to rev at least another 700rpm, assuming you have cams to take advantage of it.
 

·
Registered
Joined
·
312 Posts
Discussion Starter #19
You think....and i know :).
The .2 liters of displacement is very important to me.
There is so much more touque in a 3.0 12v compared to a 2.8 12 v.
The 3.0 crank kan easily do my rpm goal.
I will make a 3.2l engine so i cant use the 5m crank.

I also thought about building a quardratic engine using the 5m crank and then bore to 85mm.
Then the bore stroke will be 85x85....but that is dropped again.
 

·
Super Moderator
Joined
·
10,546 Posts
I still say thats a better way to go. You'll still have almost 3.0ls and a nice square bore to stroke that can rev. Don't forget a 2jzgte has an 86x86mm bore to stroke and fuel cut is somewhere around 7500rpm. The 5m hybrid with its slightly smaller dimensions and nice light aftermarket internals could possibly be very reliable up to 8000rpm.

To be honest I can feel the torque difference between a 6m and 5m, but its really not that big of a power increase and the dyno agrees. I think the revs would be a bigger benefit, but thats just my opinion.
 
1 - 20 of 89 Posts
Top