Author Topic: 2,1l turbo engine (Read 5770 times)

maarten1802 · « **on:** July 27, 2008, 12:49:48 PM »

hello i,m maarten from holland

i,m new to this forum

my cars :

bmw 1802 1973 with m42 engine
bmw 1802 1971 project car
bmw 323i almost finisht

i want to build a 2.1l turbo engine for my project car

the m42 engine i,v allready got

i,ve got a turbo from a volvo s80 2.4t td04hl-13t
a intercooler from a landrover

and i want to build a megasquirt on it with lpg injection

i.m want the compresion ratio 1:8

are there more turbo 2.1 engine.s on this forum

what kind of pistons do they use

this is my daily driver not perfect yet but work in progress

hesgone2fast · « **Reply #1 on:** July 27, 2008, 02:49:58 PM »

Hello, you have a nice one up here:

http://www.r3vlimited.com/board/showthread.php?t=84137

MM 2.1L turbo engine uses a 86 mm Forged Alusil Piston designed specifically
for boosted engines with 8.6 compression ratio that has a flat top and no valve pocketing. The crown thickness at .080 is 2 mm thicker than their
normally aspirated pistons.
I hope this helps.

maarten1802 · « **Reply #2 on:** July 27, 2008, 04:52:32 PM »

thanks for the info

did he use the m47 crank and stock conrods?

i coudn,t find the info in the topic

hesgone2fast · « **Reply #3 on:** July 28, 2008, 02:58:34 AM »

You have all the info you need in the pdf article Metric Mechanic has about the M42 on their website: http://www.metricmechanic.com/
The 2.1L Metric Mechanic turbo engine uses the M47 crank, custom rods and custom pistons.
You can�t use the stock rods with the M47 crank for a turbo application. because:1- that combo would yield a compression ratio of no less than 10:1
I have the M47 crank, with stock M42 rods, and 3.2L M3 pistons(very shaved)
and have 11,5:1 with no turbo of course...You could use custom pistons, but still... 2-the stock M42 rods(not forged) would not be very reliable for a high boost application in junction with the M47 crank (forged) I�m not saying it can�t be done, just saying it wouldn�t last long I think.
Just my thinking, if something of the above is wrong, please correct me.

maarten1802 · « **Reply #4 on:** July 28, 2008, 11:04:32 AM »

maybe I can use m3 rods ?

rob_e30 · « **Reply #5 on:** July 28, 2008, 01:25:53 PM »

Stock M42 rods are forged and can be used with custom pistons to lower the CR. The stock CR for an M42 is 10:1

strypt · « **Reply #6 on:** July 30, 2008, 05:42:05 AM »

Quote from: maarten1802;53907

maybe I can use m3 rods ?

No, euro M3 rods have a larger diameter bearing and wont fit the M47 crank.

hesgone2fast · « **Reply #7 on:** July 30, 2008, 07:47:13 AM »

Stock M42 rods are not forged, I�m pretty sure of this, the only thing forged on the M42 is the crank.
I have a set of M3 rods from a US spec S50 which has the same bearing as the M42, and same piston pin diameter as well. They are 135mm in lenght (M42: 140mm) So yes, you could use these rods with the M47. But the problem would be the piston sitting too low on the bore at BDC. it would be 8,5mm lower than in a stock M42, I don�t know how safe is that, because part of the piston skirt would be hanging out of the bore
Metric Mechanic has custom rods and piston that work perfectly with the M47 crank and turbos.

halcron · « **Reply #8 on:** July 30, 2008, 09:38:12 PM »

Quote from: hesgone2fast;54034

Stock M42 rods are not forged, I�m pretty sure of this, the only thing forged on the M42 is the crank.
I have a set of M3 rods from a US spec S50 which has the same bearing as the M42, and same piston pin diameter as well. They are 135mm in lenght (M42: 140mm) So yes, you could use these rods with the M47. But the problem would be the piston sitting too low on the bore at BDC. it would be 8,5mm lower than in a stock M42, I don�t know how safe is that, because part of the piston skirt would be hanging out of the bore
Metric Mechanic has custom rods and piston that work perfectly with the M47 crank and turbos.

Nope. Stock M42 rods are forged. Only the piston is cast. There are people here who have done over 20psi on stock rods.

rob_e30 · « **Reply #9 on:** July 31, 2008, 12:09:49 PM »

Quote from: halcron;54075

Nope. Stock M42 rods are forged. Only the piston is cast. There are people here who have done over 20psi on stock rods.

There are even some of us who have seen 27psi (on stock rods).