Best camshaft for m20 2.7i motor

[Smash9002]

I have a 2.7i motor that I just yanked out of my 88 325 for a refresh. The motor is an 88 m20b27 super eta block and pistons with an 89 top end on it, with "i" DME, intake, throttle body ets..

I had the cylinder head resurfaced when I did the topend conversion, I don't remember how much..

I'm putting on a better quality head gasket and thinking about ARP head studs, and an adjustable cam gear to compensate for the material removed from the cylinder head. While I'm there I'm considering upgrading the camshaft. The car is daily driven, has AC, and I don't want to have any issues with tuning, I have a second e30 for that.

What's my best bet for a camshaft for an otherwise stock 2.7i? Should I mess with an adjustable cam gear? Are there any other things I need to think about doing to make good use of the cam and wake the motor up a little?

I'm considering the Miller MAF conversion as an option for this car.. but want to come up with a total package before I just start ordering parts.

Any input will be greatly appreciated!

[digger]

a schrick 272 will work ok, or even a 284/272 but remember to check piston to valve clearance. forget about the ARP they aren't cheap and use the money for general maintenance and freshen up, a cam gear is a good idea

[Smash9002]

a schrick 272 will work ok, or even a 284/272 but remember to check piston to valve clearance. forget about the ARP they aren't cheap and use the money for general maintenance and freshen up, a cam gear is a good idea

Thanks! I'll check out pricing on the 272 and 284/272. Good to know the ARP's are not worth it, that's a good chunk of change that I could use elsewhere. Anyone have a good cam gear to recommend? From what I hear, I need to be careful with which one I buy. I see them from around $90 to $250 for the Vac Motorsports one, seems excessive.. but I don't want to skimp out and risk hurting my engine. I love my m20 :)

This may be a noob question.. but does anyone run a windage tray/ oil pump baffle in their oil pan on a dd? IE has them for sale, seems pretty cheap for some good insurance to keep my motor from getting oil starvation.

[digger]

Thanks! I'll check out pricing on the 272 and 284/272. Good to know the ARP's are not worth it, that's a good chunk of change that I could use elsewhere. Anyone have a good cam gear to recommend? From what I hear, I need to be careful with which one I buy. I see them from around $90 to $250 for the Vac Motorsports one, seems excessive.. but I don't want to skimp out and risk hurting my engine. I love my m20 :)

This may be a noob question.. but does anyone run a windage tray/ oil pump baffle in their oil pan on a dd? IE has them for sale, seems pretty cheap for some good insurance to keep my motor from getting oil starvation.

plenty of people have used the correct factory head bolts with success. if you were going FI it would probably be worth it

[MR 325]

Agreed, only go with the ARP if you're adding boost. Otherwise, stock replacement bolts will do the trick.

For the camshaft, I agree with the above. Something in the 272-274 range would be great.

You don't need an adjustable cam gear to compensate for decking a head, don't waste your money.

[Smash9002]

It seems like the 284/272 may be overkill for my application, however I don't want to pass up an opportunity for more power. Shrick seems to recommend their valve springs either way, 272 or 284/272, and I don't want to have to baby it.

Mr 325, have you had any experience with adjustable cam gears that makes you feel they are unnecessary?

I put 20k on my current setup after machining the head, it worked fine.. I broke a motor mount and the head gasket started seeping out the side of the block, so I pulled the motor. This go around I want to squeeze every bit of power I can get.

[digger]

It seems like the 284/272 may be overkill for my application, however I don't want to pass up an opportunity for more power. Shrick seems to recommend their valve springs either way, 272 or 284/272, and I don't want to have to baby it.

Mr 325, have you had any experience with adjustable cam gears that makes you feel they are unnecessary?

I put 20k on my current setup after machining the head, it worked fine.. I broke a motor mount and the head gasket started seeping out the side of the block, so I pulled the motor. This go around I want to squeeze every bit of power I can get.

based on the 885 head flow numbers (exh/int ratio) a non split duration cam like a 272/272 makes more sense IMO but the 284/272 does work well and many have used it with good sucess. you can get away without the adjustable cam gear if you have only skimmed the head and not decked the block but if you look around for a decent quality afforable one it can unleash some hp if you have the money to do some dyno time. New stock valve springs are fine but they must be new

[Smash9002]

Thanks for the help guys.

I've been doing as much research as I can on the different m20 variations offered over the years. From what I gather, my 2.7i motor is an 8.5:1 low compression motor, as is a USspec m20b25 from a 325i. Im seeing more opinions that point toward the m20b25 US motor having better performance than my frankenstien 2.7i. If that's the case, Ill switch back to the b25 bottom end. What say ye, r3vlimited?

Does it make sense to put an expensive cam in such a low compression motor?

[PeteD]

I did a lot of the same research you did, and read a lot of the same, widely differentiated opinions (The only consistency I read, was the motor felt like it had more torque). Because of this, I was hard pressed to draw any real conclusion, however the m20 market is poised to best serve the 2.5 motors. Even companies like Metric Mechanics, build stroker kits for the 2.5 block, not the 2.7.

I think the bottom line is how good/knowledgeable the person building the motor was; meaning, putting the extra hours in the machine shop to where need be with the 2.7i.

and to qualify my post: I've never done this, I dropped in an s50/m50 (frankenstein pretty much) instead. But I still love the m20's! haha

[Smash9002]

Hmm.. for how many 2.7i motors people have built we need a more solid knowledge base for the super eta/ i topend combo. I think ill switch back to.the 2.5 and see how I like it, and save my camshaft allowance for the 3.5 im putting in my other e30...

[tinkwithanr]

Just so you know you will be loosing power going back to the 2.5L bottom end. The majority of people that do the 2.7L swap use the regular eta bottom end, which results in a C.R. of ~8.0. While great for a boost application, it lacks power when compared to the higher compression of the 2.5L. But, since you based yours on the super eta bottom end, you didn't looks any compression going to the 885 head. This means that you should be putting down a noticeable amount more power compared to a stock M20B25. The only reason I could see for going back to 2.5 bottom end would be if it was in much better condition than your 2.7 in there there now.]


As far as what modifications would go well with your motor, a camshaft should probably be lower on the list depending on what else you already have. The stock cam works fine with the stock CR, and and aggressive cam (anything above a 272 really) would be a waste without a higher CR. I would put that money towards making sure the head is as new (valve seals, rockers etc) and then look at some options for headers or the MAF conversion like you mentioned. Both of those things would probably give you better results on the butt dyno. Also, like others mentioned above, the ARP hardware is very unnecessary unless your going for boost. Save that money for other stuff.

My .02

To qualify my post: I've been researching the different M20 options for the past two years, and am currently building up a 3.2L M20 with billet rockers, itb's, 288 schrick etc etc. While I haven't personally build a 2.7i, I do have a good understanding of their differences and variations.

Edit:
Also, the above statement about the aftermarket serving the 2.5L more than the 2.7L is not really applicable in this case. Yes, there are not many aftermarket parts made for the stock, 2.7L eta engine. However, the 2.7i stroker like you have would be able to use any aftermarket part that a regular 2.5L engine could use. The ONLY difference (assuming you did the head swap properly, including the 'i' intake manifold and exhaust manifold etc etc) is the throw of the crankshaft and the length of the connecting rods. Both of which have no effect on bolt on parts.

[PeteD]

^ good point, you already have the stock "stroker" because of the 88. I've been in a 2.5 with a polished/ported 885 head, 272 cam, and MAF chip & intake, headers etc. Thing was a beast! I would imagine you can add the same mods.

[Smash9002]

Just so you know you will be loosing power going back to the 2.5L bottom end. The majority of people that do the 2.7L swap use the regular eta bottom end, which results in a C.R. of ~8.0. While great for a boost application, it lacks power when compared to the higher compression of the 2.5L. But, since you based yours on the super eta bottom end, you didn't looks any compression going to the 885 head. This means that you should be putting down a noticeable amount more power compared to a stock M20B25. The only reason I could see for going back to 2.5 bottom end would be if it was in much better condition than your 2.7 in there there now.]


As far as what modifications would go well with your motor, a camshaft should probably be lower on the list depending on what else you already have. The stock cam works fine with the stock CR, and and aggressive cam (anything above a 272 really) would be a waste without a higher CR. I would put that money towards making sure the head is as new (valve seals, rockers etc) and then look at some options for headers or the MAF conversion like you mentioned. Both of those things would probably give you better results on the butt dyno. Also, like others mentioned above, the ARP hardware is very unnecessary unless your going for boost. Save that money for other stuff.

My .02

To qualify my post: I've been researching the different M20 options for the past two years, and am currently building up a 3.2L M20 with billet rockers, itb's, 288 schrick etc etc. While I haven't personally build a 2.7i, I do have a good understanding of their differences and variations.

Edit:
Also, the above statement about the aftermarket serving the 2.5L more than the 2.7L is not really applicable in this case. Yes, there are not many aftermarket parts made for the stock, 2.7L eta engine. However, the 2.7i stroker like you have would be able to use any aftermarket part that a regular 2.5L engine could use. The ONLY difference (assuming you did the head swap properly, including the 'i' intake manifold and exhaust manifold etc etc) is the throw of the crankshaft and the length of the connecting rods. Both of which have no effect on bolt on parts.

Thanks, that's quite helpful. The car is an 88 325 "super eta". I also have an 89 325i, which is where I got all of the topend parts, cylinder head/camshaft, dme, intake, throttle body, etc. I'll stick with the 2.7 bottom end and put the motor back together with some new gaskets. The whole reason I took the motor out is because the head gasket started seeping ever so slightly out the side of the block, and a few too many 5500 rpm clutch dumps resulted in a broken motor mount. I'll most likely do a MAF conversion and rebuild my other cylinder head on the side, with a port and polish, and either a 272 or a 284/272 cam. Then when I'm ready to install the built cylinder head I can think about a new set of pistons.

I also have an m30 waiting to go into one of my e30's, but I cant decide if I should cam that motor or run it stock. And I don't have the money to build out the m30 AND m20!

^ good point, you already have the stock "stroker" because of the 88. I've been in a 2.5 with a polished/ported 885 head, 272 cam, and MAF chip & intake, headers etc. Thing was a beast! I would imagine you can add the same mods.

I love the power the 2.7i budget stroker makes, but at the same time it really feels like there is more to be squeezed out of it!

[MR 325]

I was hard pressed to draw any real conclusion, however the m20 market is poised to best serve the 2.5 motors. Even companies like Metric Mechanics, build stroker kits for the 2.5 block, not the 2.7.

Well, the blocks are exactly the same.

[Smash9002]

Looks like the 2.7i motor is going back in my car with a new head gasket, motor mounts, and all the related seals. Ill snap some pics and post em up. Hopefully this thread will be useful to others in the future who find themselves in my situation. I basically concluded that a camshaft would not be money well spent on a "budget" stroker. My plan is to spend my money a little more wisely on maintenance and a miller maf conversion. I already have Bavauto headers, so ill get some exhaust made up to go with those. Ill report back when done.. Id be really stoked to get some dyno time so people will know what to expect from a frankenstein 2.7i..