I am looking into a m20 stroker as i would like to keep the m20 and realise this path will be more costly, so i have been looking at the IE kits online and also have read the DIY threads which by the sounds of it maybe the way to go, but in terms of power and reliability, is there much gain in a 3.0 or 3.1 stroker over the 2.8. Any info would be much appreciated.
Cheers guys
M20 2.8 stroker vs 3.0 or 3.1 stroker
Moderator: martauto
-
87mtech27
- E30 Zone Camper
- Posts: 1429
- Joined: Mon Feb 02, 2009 11:00 pm
From my understanding there isn't much point going beyond 2.8 as the head starts restricting air flow thus you end up spending a lot more money after a 2.8 stroker for very little gain.
At a guess if everything is set up properly on a 2.8 stroker you'll be hitting 200bhp whilst a 3.1 stroker you'll but the wall at 220-230bhp.
Personally I would use a 2.7 81mm crank, 135mm rods and custom pistons which should see you at 200bhp easily.
Have a read through HairyScreech thread on here and "digger" thread for better info.
Reggid should be able to shine more light on here.
At a guess if everything is set up properly on a 2.8 stroker you'll be hitting 200bhp whilst a 3.1 stroker you'll but the wall at 220-230bhp.
Personally I would use a 2.7 81mm crank, 135mm rods and custom pistons which should see you at 200bhp easily.
Have a read through HairyScreech thread on here and "digger" thread for better info.
Reggid should be able to shine more light on here.
-
reggid
- E30 Zone Squatter
- Posts: 1983
- Joined: Mon Jul 11, 2005 11:00 pm
- Location: Oz
What are you goals for power? what kind of engine (street, race etc)?
All else equal the 3.0L or 3.1L will give noticeably more midrange torque which you will feel on the road than the 2.8L , the increase will basically follow proportionally to displacement if not more if you do it properly, so an extra 30lbft is not out of the question.
At the topend the hp will be closer between the 2.8L and 3.1L as you start to run into breathing issues so things like head work and higher duration cams are a must with the bigger strokers if you want the normal m20 powerband.
A 3.1L will have peak hp at a lower rpm which is good for a street car but if you like revving an engine to 7500 then a big stroker will be a lot of $$$ to achieve that where as the 2.8L will inherently need a few more revs to make the power.
If you go IE speak to Andrew and ask for his new OEM piston shape, don’t get the kit, just get pistons from him and source a crank (m54b30) and 24V rods locally, shipping will be a $$$ for a near 60lb crank.
All else equal the 3.0L or 3.1L will give noticeably more midrange torque which you will feel on the road than the 2.8L , the increase will basically follow proportionally to displacement if not more if you do it properly, so an extra 30lbft is not out of the question.
At the topend the hp will be closer between the 2.8L and 3.1L as you start to run into breathing issues so things like head work and higher duration cams are a must with the bigger strokers if you want the normal m20 powerband.
A 3.1L will have peak hp at a lower rpm which is good for a street car but if you like revving an engine to 7500 then a big stroker will be a lot of $$$ to achieve that where as the 2.8L will inherently need a few more revs to make the power.
If you go IE speak to Andrew and ask for his new OEM piston shape, don’t get the kit, just get pistons from him and source a crank (m54b30) and 24V rods locally, shipping will be a $$$ for a near 60lb crank.
E30 325is with M20B31
-
e30lyfe
- E30 Zone Newbie
- Posts: 9
- Joined: Mon Mar 02, 2015 11:00 pm
Yeah the plan is just for a daily driver at the moment so mid range torque would be better for my needs. It is a m20b20 at the moment but would like to build it myself over my university break, and will be learning as i do it. I assume it would be worth investing in an 885 head aswell? Another question on the ECU front is it best to keep the motronic or go aftermarket?
-
reggid
- E30 Zone Squatter
- Posts: 1983
- Joined: Mon Jul 11, 2005 11:00 pm
- Location: Oz
do a big stroker then, you can use a 320i (731) head but it needs to be well ported by someone competent with oversized valves etc this way you can use a flat top piston. the 885 needs a different piston shape.
if you want an 885 id buy a tired m20b25 and strip it down that way you dont need to overbore it so much and you can drive your car while you work on it
if you want an 885 id buy a tired m20b25 and strip it down that way you dont need to overbore it so much and you can drive your car while you work on it
E30 325is with M20B31
-
e30lyfe
- E30 Zone Newbie
- Posts: 9
- Joined: Mon Mar 02, 2015 11:00 pm
Thanks mate your a legend cheers for all the info. Do you have a build thread or anything around?
-
reggid
- E30 Zone Squatter
- Posts: 1983
- Joined: Mon Jul 11, 2005 11:00 pm
- Location: Oz
E30 325is with M20B31