Stroker Part Questions (2.7i via M52 crank?)

[Sykohtic]

I’m along way from being an expert on blower cams but you may want more exhaust duration and maybe wider lobe centers. ENEM do the Z45 cam for a FI application which is nothing more than the NA cam with wider lobe centres. I think it’s a turbo cam but should work well enough. using it in a NA engine should make the idle and drivability better to, but won’t make the same torque. A schrick 272 will be ok for any engine to

The length of the runners tune for about 5500rpm and the runners internally are not great in some areas as they have weird bends and inflexion shape (cut one open you'll see) and they dont align as well with the ports compared to a aftermarket intake from RHD. you could buy the RHD intake manifold and some extensions (without throttles) and fab a plenum with as long runners as you can fit for single throttle body and it would work great.

You’ll definitely want something for engine management if you’re going to use a blower. PNP MS is pretty affordable. On motronic you can run a chip if NA but you leaving a lot of power on the table and drivability will be inferior. In general with OEM manifold and big cam the drivability is nowhere near as nice as it is with ITB thats one of the big advantages and reasons for ITB.

I agree that with FI I'll need a standalone. MS is very affordable for all its capability, but on a budget 800 bucks eats away at the funds. I'll absolutely go to such a unit when I eventually do go FI, but right now for NA I just want it to run. It wont be optimum to run it via Motronic and chip, but then again every motor stock is probably leaving a few extra horsepower on the table using standard Motronic to begin with. It can run on Motronic temporarily until I put back the money for the standalone.

I like the idea of the RHD intake manifold with extensions. As I love my Toyotas, an easy design to replicate is the old Supra intakes; literally a big tube with some angling cut into the back and runner out the side and a TB on the front. Then its a simple task of sizing the pipe so air velocity isn't total garbage and making the angle over the rear 3 ports such that I dont slow the air down too much back there. Once theres boost it wont really matter too much, and its no precision intake, but it should be functional and allow for better flow.



I emailed whodwho about cams this morning, haven't gotten a response yet but I'm sure he has some valid info to add.

The turbo cam idea is something I'm not sure I agree on. I don't have the real world experience to back it up really, but in my mind with a technical understanding, turbo cams have greater exhaust duration to help with turbo spooling. Its designed so that it spools and keeps spooled the turbo which provides intake boost to overcome the extra exhaust losses. I.E. a turbo cam is meant to spool up the turbo to 0.5 bar and then it overcomes the abundance of exhaust duration by forcing in more air consistently and therefore making more combustion. With a blower you need power to make power. The boost is linear instead of plateau shaped. So, if the blower makes the same 7lbs at the top of the RPM range, and it take 0.5 bar to overcome the exhaust losses, then the car will only be coming into power up at the very top, which in my mind looks like a peaky curve as opposed to the goal of a linear curve. Turbos can afford to sacrifice power off boost because when spooled their boost is approximately constant. And please don't take this as me trying to shit on your ideas or opinion or sound like a know-it-all, it's completely geared as a debative counterpoint. I'm learning, and could very well be very wrong. lol

On a note about FI, I found a cool intercooling idea using old SAAB intercoolers. It might not flow the absolute best but it's cool that it's so compact and nifty.

[digger]

I agree that with FI I'll need a standalone. MS is very affordable for all its capability, but on a budget 800 bucks eats away at the funds. I'll absolutely go to such a unit when I eventually do go FI, but right now for NA I just want it to run. It wont be optimum to run it via Motronic and chip, but then again every motor stock is probably leaving a few extra horsepower on the table using standard Motronic to begin with. It can run on Motronic temporarily until I put back the money for the standalone.

I like the idea of the RHD intake manifold with extensions. As I love my Toyotas, an easy design to replicate is the old Supra intakes; literally a big tube with some angling cut into the back and runner out the side and a TB on the front. Then its a simple task of sizing the pipe so air velocity isn't total garbage and making the angle over the rear 3 ports such that I dont slow the air down too much back there. Once theres boost it wont really matter too much, and its no precision intake, but it should be functional and allow for better flow.



I emailed whodwho about cams this morning, haven't gotten a response yet but I'm sure he has some valid info to add.

The turbo cam idea is something I'm not sure I agree on. I don't have the real world experience to back it up really, but in my mind with a technical understanding, turbo cams have greater exhaust duration to help with turbo spooling. Its designed so that it spools and keeps spooled the turbo which provides intake boost to overcome the extra exhaust losses. I.E. a turbo cam is meant to spool up the turbo to 0.5 bar and then it overcomes the abundance of exhaust duration by forcing in more air consistently and therefore making more combustion. With a blower you need power to make power. The boost is linear instead of plateau shaped. So, if the blower makes the same 7lbs at the top of the RPM range, and it take 0.5 bar to overcome the exhaust losses, then the car will only be coming into power up at the very top, which in my mind looks like a peaky curve as opposed to the goal of a linear curve. Turbos can afford to sacrifice power off boost because when spooled their boost is approximately constant. And please don't take this as me trying to shit on your ideas or opinion or sound like a know-it-all, it's completely geared as a debative counterpoint. I'm learning, and could very well be very wrong. lol

On a note about FI, I found a cool intercooling idea using old SAAB intercoolers. It might not flow the absolute best but it's cool that it's so compact and nifty.

my understanding is turbo cams often use wider lobe centres and are dialled in advanced so the intake lobe is positioned much like a NA cam but the exhaust is advanced inherently by doing this so the early exhaust opening spools turbo "earlier". its more about the timing of the exhaust events than the duration for spool. the catcams turbo cams have smaller exhaust lobes and the enem ones are the same lobes as the NA cams but different valve events. supercharger cams on the other hand do often have bigger exhaust duration

[TrentW]

I have an M52 crank. So no counterweight modding is necessary with i pistons?

Are the Seta rods more desirable than S50 rods? I'm looking at a 272 cam and run NA with Motronic and a chip. This is a street car, so I'd like to retain driveability close to stock. MS is not ruled out if I get a bigger bang for the buck, but I don't want to fall into "Stroker Debt" on the credit card.

[digger]

you need 130mm rods these come on ETA, SETA, M20B20 and M20B23. to use a 135mm rod you need custom pistons

[Sykohtic]

I've been emailing back and forth with whodwho, so here's that conversation. He approved my quoting the emails :) I am waiting for a response to my most recent. I have quoted all the lines in the emails that were not either introductory or not to do with the response (things like greetings or names have been left out for obvious reasons).

Sykohtic:

I've talked to you before on r3v about blowers for the M20. I'm in the process of gathering parts for a stroker build that will likely by SC down the road. I plan to use an M62 blower, and run around a bar with it. Right now I'm trying g to select a cam that will work with my NA setup but can also work with the blower down the line.

I was thinking of going to a 290 cam, which is pretty large, due to all the extra intake duration. My question is what should I be looking for with a positive blower as far as cam? Digger recommended a ENEM Z45 style cam like is used in turbo cars with more exhaust duration with basically stock intake duration, but to me that sounds like torque loss and a weird power curve with a positive blower that makes peak power at the top of the rpm range. I'm sure it would be more friendly that way, but not make the same power. Goals with the blower are around 270-300 wheel. NA goals are kinda whatever. I've been told that an NA stroker using the m52 crank can make 180-220whp depending on peripherals and cam. I suppose 200whp would be great if I got there.

I am on a budget so the cam will be regrind. But that also means I can tell the grinder whatever degree I want and they'll do it.

Budget is also the reason that boost isn't coming until much later when I have much more money to play with.

Whodwho:

I did a bunch of research on this a few years ago but that knowledge has faded on being able to rattle off facts and details. I don't think that big of cam is needed or desired, unless you are just looking for overall HP. With boost I feel the need for trying to improve air pumping is less critical and concentrating on power delivery and drivability is more important.

For my setup I think a big cam would of been counter productive, you loose lower end torque and then a big surge as the cam and boost comes on. I tried something different and went the opposite direction and put a smaller cam in. I am using a SETA cam which is less duration but higher lift then a stock 325i cam(I don't remember the LSA but think it was slightly wider). This gave me a nice flat torque delivery and still was making power at 6300 if I remember correctly. I do believe it was holding back overall HP but I was looking for drivability. I was making ~250 on 10-12 psi on that setup.

This will be different with a positive displacement SC vs a centrifugal type like I was running so it won't be an accurate comparison. With a positive displacement one I believe it will act like an increased displacement engine and may ok with a bigger cam but still not thinking that much. With the increased stroke it will take to a slightly bigger cam. I am not that keen on using a turbo cam, they are usually designed with opposite characteristics needed for a SC in my opinion.

I also think you will be limited to what duration you will be able to get out of a regrind on the cam and stay in usable geometry

Bottom line I think you would be happier going closer to stock then going crazy on a big cam.

Sykohtic:

Thanks for the response. That's extremely helpful. And before I continue, would you mind if I quoted your response email in the forum for universal reference?

You make really good points. I feel like I do dare venture I to a larger cam, but for FI purposes as you said maybe one that's not so big as 290. The more I learn, the more I think building an engine once to do two jobs well is going to be difficult, especially on a tight budget. Building it once would infer putting in an MLS Head Gasket and a set of head studs as well. All very worthwhile endeavors that are worth it in the long run but that aren't necessary for the NA application, though I know it's always nice to have such things.

I'm starting to feel as if maybe it's better to build the stroker and enjoy it until I have the money for a purpose built cam, head studs, good quality MLS gasket, good standalone etc. This will be my first foray into building a motor for myself, so taking on too much trying to build a dual purpose motor all at once might be a bad idea.

250 wheel (I'm assuming) hp is great, especially when your goals were drivability over maximum horsepower. I might tend to creep a few more inches towards the horsepower side, but I definitely agree that there's no point in a million HP without being able to use it.

I have an idea that could make a somewhat large cam a bit more friendly. Adjustable cam gears are something I've been researching lately. And with good quality products like the nuke gear readily available, I've been wondering if it could be money well spent if larger cams are in the picture. Understandably I could put that money into head studs or an MLS gasket instead, but I figured it was a usable upgrade for adjusting a roots setup's power curve as well.

Whodwho:

If you are going with the budget stroker and not buying custom pistons and all I think you building it NA for now and you can change the head out later with a different cam and add studs and gasket then makes sense. If building it for both then running around 9-10:1 compression with a mild cam would work NA and still work with mild boost. I think having an adjustable cam gear is a good addition to any custom engine build, I have a Nuke one myself and the ebay style one from IE.

You should not have an issue hitting over 250 with a normal cam and a couple more PSI from the Eaton, mine was maxed out at that psi and I was still running on a stock headgasket and headbolts or I would of tried bumping it up some.

Sykohtic:

I'm going to be running the M52 crank, ETA rod, B25 piston combo. There might be some shaving of the block just to optimize the setup a little, depending on that cost. Several sources on the internet and forums place the compression with this stroke around 9.5:1. So with compression there it should be about right then. The m62 blower I want to use causes less parasitic loss and takes up less space than an M90, loses thermal efficiency at about the point where it would deliver 15 lbs of boost so about a bar is all I want to run to give me a few hundred or so RPMs of margin for a hot summer day.

Do you have any ideas for "budget" water meth injection? Or would you just buy a pre-built setup?