M20 B20 Options (Again!!)

[jbh]

for a cheap power increase id go for the 2.7 if i had a spare grand id build a 2.8

[stonesie]

for a cheap power increase id go for the 2.7 if i had a spare grand id build a 2.8

What he said, even a basic 2.7 will (with a nice cam) be a massive leap ahead of a 2.0... Talk to Ant about a catcam and a suitable chip to run it.

[AlpineAde]

theres no replacement for displacement lol

True enough, mate.

The cost for me to do a 2.8 compared to a 2.7 has crossed the the "don't worry about it" stage. Economically, for a little more you'd do the 2.8. A 2.8 would cost me a couple of hundred more ~ the 2.7 isn't a worthwhile proposition anymore ~ at least to me.

What interests me is 2.9-3.1. Yum! That's whee it's at!

On the basic terms, though ~ bang for buck: 2.7 will get you what you want at the price-point you want.

[johnt0709]

the 2.8 m20 is a better choice in my opinion if you want a stock looking m20 as it will give the best gains.

i have m52b28 cranks quite often if required and could also do the conversion if needed.

Thanks wullie - this option would require the b25 pistons - look for more hp for less £

[jbh]

the 2.8 m20 is a better choice in my opinion if you want a stock looking m20 as it will give the best gains.

i have m52b28 cranks quite often if required and could also do the conversion if needed.

Thanks wullie - this option would require the b25 pistons - look for more hp for less £

again doing this involves doing a complete rebuild. as your changing rods and pistons your then looking at big end bearings , small end bearings, piston rings, a cam that will release the power of the 2.8 and as its been said else where you ll need to run custom management to get over 200 bhp which again involves rr time to get it set up and running correctly. could run into 2k by the time you start building by the time you have it in the car and running the way you would be happy with... hence the reason I'm going down the 2.7 road.. I've sourced an eta bottom end and have everything else i need. and as stated I can lay my hands on another one if required.. i can also lay my hands on a complete 2.8 24 valve lump for much cheapness ..

[johnt0709]

James - pmd you about the eta

[wullie325i]

2.7 is definetly the way to go then if you want more power at low cost but you will only get out what you put in though.

the b25 head is a better idea than the b20 but you could swap it over at a later date when funds allowed as im sure the 2.7 b20 combo will still be a fun grunty car and a big improvement over m20b20 power lol.

good luck with whatever you decide and im here if you need and help/advice.

[chris_335]

M20 B20 30 quid before christmas and its yours all the parts you need was going strong no noise 110k

[johnt0709]

M20 B20 30 quid before christmas and its yours all the parts you need was going strong no noise 110k

Thanks but i already have a b20 that I would use

[wullie325i]

M20 B20 30 quid before christmas and its yours all the parts you need was going strong no noise 110k

Thanks but i already have a b20 that I would use

if you had another b20 spare you could build it up slowly as funds allowed into a b25 2.7 or 2.8 while using the budget 2.7 you are going to do.

30 sheckles is cheap for a working motor although a b20 aint worth much to most people even though it is a decent enough engine but not against its b25 brother

[wullie325i]

when you are doing the b20 2.7 fire on a 325 throttle body to help it breath and have it bored out if you can.

are the b20 and b25 inlet manifolds the same size? as if not a b25 inlet manny would be a good idea too.

its been so long since i have seen a b20 lol.

[chris_335]

well mine is sat there looking sorry for its self

[zqeexz]

I would go the 2.7 route now using the 320/323 head, then build a 2.8.

If you are going to stick with the 2.7, then build it properly with the 325 pistons and head, people underestimate how important squish is in getting a motor to perform properly, using pistons not matched to the head is IMO.

But if you use the Eta pistons, do they not match the 731 head?

[dazleeds]

forget aged b20 b25 time to move on folks m52 all the way

[zqeexz]

I would go the 2.7 route now using the 320/323 head, then build a 2.8.

If you are going to stick with the 2.7, then build it properly with the 325 pistons and head, people underestimate how important squish is in getting a motor to perform properly, using pistons not matched to the head is IMO.

But if you use the Eta pistons, do they not match the 731 head?

Yes they do, but you are building a motor with an inferior head, if you use the 325 pistons and head, you get a system that flows much better and therefore will have more power. You will need to deck the block and use a vernier pulley but the end result will be much better.

Some are using the 325 head with non-325 pistons, that will seriously affect squish.

That’s ok then, gave me fright for a minute, because I am doing a build in the new year with Eta pistons and a 731 head, I know what you mean by the 731 being inferior to the 885 but if you’re starting point is a b20 then I think the 2.7 with the 731 head makes the most since (provided the existing 731 head is in good condition), if I was starting with a b25 and I had an 885 head than I would do a 2.8

[johnt0709]

But if you use the Eta pistons, do they not match the 731 head?

Yes they do, but you are building a motor with an inferior head, if you use the 325 pistons and head, you get a system that flows much better and therefore will have more power. You will need to deck the block and use a vernier pulley but the end result will be much better.

Some are using the 325 head with non-325 pistons, that will seriously affect squish.

That’s ok then, gave me fright for a minute, because I am doing a build in the new year with Eta pistons and a 731 head, I know what you mean by the 731 being inferior to the 885 but if you’re starting point is a b20 then I think the 2.7 with the 731 head makes the most since (provided the existing 731 head is in good condition), if I was starting with a b25 and I had an 885 head than I would do a 2.8

Yeah sounds like the route for me - eta block b20 head, only thing i considered that wullie had mentioned was the throttle body from a b25 - would this make much impact?

James - pmd you re the block.

[zqeexz]

Regarding the throttle body yes IMHO, you need to get the b25 inlet manifold for the the injectors anyway so it normally comes with the b25 throttle body attached, does not cost a lot either so I am going use the b25 throttle body on mine.

What cam are you thinking of using?

[johnt0709]

Do you need to change the cam? Or is this a luxury my wife will say I cant afford?

[timsands]

can you put an eta crank into a standard b25 engine, making it a stroker?

[zqeexz]

Re: johnt0709 question, A b25 cam is the lowest you should be going for, I dont think a b20 cam would work well in 2.7, you need to decide this before getting your custom ECU chip from Ant.

Re: Timsands question, have a read of http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.7

As it explains it all in detail, personally if had a b25 I would build a 2.8

[johnt0709]

No mention of changing the cam in the wiki article? Does this need to be done?

[zqeexz]

No mention of changing the cam in the wiki article? Does this need to be done?

Up to you I suppose, but I have never heard of anyone sticking with the b20 cam, I have an old article from Total BMW about 2.7 and 2.8 m20 builds and in the 2.7 example the start point was a b20 and they used a b25 cam but a lot of people have used higher cams than that. I will be using a b25 cam myself.

[johnt0709]

Thanks - Ill look into this further.

[johnt0709]

James (JBH) - still able to source an eta block?

[jbh]

James (JBH) - still able to source an eta block?

will get it in my possesion after the new year.. ill be using the b2.5 cam in mine unless i can get a cat cam cheaply

[johnt0709]

James - no thats cool - just let me know when you have the block - i can pick up

[Millsand]

My 2.0 was bored out to 84mm and with the aid of crank/cam/pistons its now a healthy 2.8 circa 200bhp.

Bang for buck

Is that all that is required for this mod? Is there a need to change injectors, air box, inlet, outlet, chip and other parts to achieve this?

[maggspower]

Holy thread revival!?

Best thing is to look in the zone wiki, the full guide is in there. But in a nut shell, no, its not that simple. There are 100 ways to build 2.7s and 2.8s, no one way is right or wrong some are just more optimised than others.

[maggspower]

http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.7

http://www.e30zone.net/e30zonewiki/inde ... ding_a_2.8

There you go a bit of sunday reading

[Millsand]

thanks, I didn't even notice it was such an old thread !