Yet another request for advice on a stroker

[ptownTSI]

I saw that someone mentioned they paid $250 for "head work and a valve job".

The power you make is going to be in the cylinder head, now I only have concrete numbers for V8 Modern Chrysler applications but a true race porting can probably carry over to other applications.

An out of the box Mopar R/T head flows about 220 cfm's on the intake side, with about $1000 worth of port work for both heads you can get that into the 305cfm range.

cliffs notes: find a good cylinder head porting shop and spend your bucks there, back cut the valves, focus on porting rather than polishing to a mirror, coat the pistons and use the most lift as possible that matches the cylinder heads flow aspects.

[Gavin]

I’m starting to assemble my DIY ITB’s now and have a question to pose for those who are wise in the ways of fuel management.

As to remove the stock 0 – 5v AFM I had planned to create a vacuum manifold, to link the 6 separate intake runners, and substitute a 0 – 5v MAP sensor for the old AFM set up. Obviously the voltage outputs of these 2 sensors will not properly overlap, so I had planned to use an APEXi Neo (in conjunction with a wideband O2) to modify the MAP sensor voltage, based on RPM, and adjust for the new fueling requirements of my system. Since I first came up with this plan however I’ve read in several spots that MAP based tuning of ITB’s can be problematic; bouncing signal, lack of vacuum, insufficient vacuum gradient, ect.

This has me thinking about a crude ‘Alpha N’ set up of sorts where I would use 0 – 5v TPS signal, referenced against RPM & modified by the Neo again, in place of the MAP signal to tune fuel. I would need to come up with some sort of correction for atmospheric pressure variation, and this system would be admittedly crude, but it seems to make sense to me. I’d be adding fuel based on throttle position, corrected for engine load based on RPM. Not an optimal way to accomplish my goal, but perhaps a functional and relatively inexpensive one.

Can anyone offer me any advice on this sort of set up?

[Gavin]

Are you able to clear your brake booster with your intended setup ?

I should have lots of room once I swap in my replacement booster/ master cylinder. I scavenged the brake guts from an older 735 (much smaller diameter unit than my stock fat boy), it should give me the clearance I need to snake a little tubing (or carbon if I decide to go that route).

I’ll be happy to post some photos of my set up once I start assembling. Right now all I have is a pile of parts (a chopped down intake manifold and a few sets of GSXR 1000 41mm throttle bodies).

[Andreas]

Andreas,

I’m planning the same injector set up you’re talking about. 12 injectors, switching over to the second up-stream set at higher RPM; but that might be a future upgrade for me. I think I’ll start by just getting things running with 6 injectors in the stock locations.

-My runners are 1.5” ID.

-I should have about 8” of runner length between the head and each TB butterfly.

-As for trumpets, I’ve got a slightly unusual plan in mind:
As my runner ID is somewhat large for the RPM I’ll be running at, I’d like to keep my total runner length (from the head to the velocity stacks) fairly long. I plan to fabricate a tubular manifold to feed the 6 TB’s that will snake out my 6 runners (at equal length/resistance-to-flow of course) to 6 separate velocity stacks and filters (I still need to figure out exactly how I’ll position these) as to give me around 20” of total length. Wide but long runners should still net me good flow characteristics, as long as I can keep my bends nice and smooth.

Let me know how your project progresses and I’ll be sure to do the same. Looks like were going to encounter a lot of the same issues.

38mm runners are just about perfect for a 42mm (less stem diameter) intake valve, I wouldn't be worried about designing extra length into the intake system. My TBs are 45mm which is in all probability too big.

We've designed an intake manifold on our CAD/CAM software to smoothly blend from the round bore of the TB to the rectangular shape of the intake port on the head. I could go and exchange my TBs for 40mm but this would make for a more difficult transition between the two shapes, especially when regarding it from a tooling / machining point of view.

That's why I am staying 45mm for now and seeing how it turns out, I can always change later. With my 304deg cam (maybe also hopelessly too big) I want to see if I can make power until about 7,500 rpm, so who knows, the 45mm might come in handy after all.

20" long intake runners, whow that's quite long. You're gonna have to twist and curve the pipes quite a bit to fit that in the engine bay ; and those bends would pretty much kill the idea of putting a 2cd set of injectors further away from the throttle plates.

Are you able to clear your brake booster with your intended setup ?

Here are some pics of my throttle bodies, I would like to see pics of yours as well ,if possible.









Here is a partially machined intake manifold. Note how we angled it so as to get the airflow as straight as possible onto the valve and thus eliminate any sharp bends for the airflow as encountered with the standard M20 intake manifold.





Here are some pictures of what BMW did with the E46 M3

[Gavin]

Andreas,

I’m planning the same injector set up you’re talking about. 12 injectors, switching over to the second up-stream set at higher RPM; but that might be a future upgrade for me. I think I’ll start by just getting things running with 6 injectors in the stock locations.

-My runners are 1.5” ID.

-I should have about 8” of runner length between the head and each TB butterfly.

-As for trumpets, I’ve got a slightly unusual plan in mind:
As my runner ID is somewhat large for the RPM I’ll be running at, I’d like to keep my total runner length (from the head to the velocity stacks) fairly long. I plan to fabricate a tubular manifold to feed the 6 TB’s that will snake out my 6 runners (at equal length/resistance-to-flow of course) to 6 separate velocity stacks and filters (I still need to figure out exactly how I’ll position these) as to give me around 20” of total length. Wide but long runners should still net me good flow characteristics, as long as I can keep my bends nice and smooth.

Let me know how your project progresses and I’ll be sure to do the same. Looks like were going to encounter a lot of the same issues.

[Andreas]

Hi Gavin

Have you given any thought to the length & diameter of your runners up to the TBs and what length trumpets you are going to use ?

Decisions you make regarding those factors will have quite an effect on air speed in the intake system. This in turn leads you to the next problem, viz. where do you locate your injectors.

Fuel atomisation is very important. If you locate the injectors far out ,e.g. outside the inlet trumpets, then at high rpm the fuel travels for a long time in high speed (and turbulent air as is passes throttle plate) allowing more time for the fuel mix evenly. The longer travel also means that the fuel can draw more heat out of the ingoing air, this improves fuel vapourization and leads to a denser air charge. All these positive influences in addition to their own benefits also allow you to safely run a higher compression ratio.

For low rpm with low air speed you need the injectors closer to the valve to work as effectively as possible.

I am going to run a dual injector setup with my throttle bodies on the 3.1 liter M20 stroker. The standalone engine management will fade out the closer injectors and inject the majority of the fuel from the outboard injectors as rpm rises.

[DrMcDave]

I know. I spent about the same on my head as the MM one, and I didn't get the x-rayed rocker arms, CNC'd ports or any of the other fancy stuff. :(

maybe i'll sell my cam and springs and just send it down there. they do produce a sick head.

[nando]

I know. I spent about the same on my head as the MM one, and I didn't get the x-rayed rocker arms, CNC'd ports or any of the other fancy stuff. :(

[DrMcDave]

I dunno, I avoided buying stuff from IE, except for my AFPR. I got all my valves from BMA, they were about half the price of the +1 valves. that adds up when you need to buy 12 of them, plus there is the valve shrouding problem to consider. I just didn't think it was worth it.

sending the head down to MM seems like a better option all the time. by the time i buy all this stuff and have it machined its going to be up there in price anyway. not sure how well that head is suited for a log manifold though, i may have to call again.

[nando]

I dunno, I avoided buying stuff from IE, except for my AFPR. I got all my valves from BMA, they were about half the price of the +1 valves. that adds up when you need to buy 12 of them, plus there is the valve shrouding problem to consider. I just didn't think it was worth it.

[DrMcDave]

so whats the argument about +1 valves. They are about the same price as stardard valves from IE. I was going to go +1 all the way around on my head, but i haven't gotten any feedback so to speak on whether its worthwhile or not. Mine will be a turbo though.

off topic - nando the 3.64 gearing is all cleaned up new fasteners on the way. also i got a new diff mount which was super expensive. i hope to have that installed before the end of november.

[nando]

yeah, there's no way I could afford to run that kind of fuel in my street car. there's a reason I have 10:1 compression and you have almost 13:1 :D

[SA E30]

SAe30 uses bigger valves on exhaust side and makes good power but you don't know whther its the valves or something else. MM use standard valve sizes so they should be fine. Bigger valves adds valve train mass too.

I use bigger valves all the way around... but the valve sizes are matched, which helps with midrange power.

The only reason I went with bigger valves was that I was already going to be making the exhaust valve the same diameter as the intake, so why not go the whole hog.

IMO, the stroker u seem 2 be building u wont really need the bigger valves, money would be better spent on a good head job and camshaft...

Make sure who ever does your porting doesn't open up the ports to much as u would be losing air speed, which reduces low end and midrange power...

Nando, we actually dont get Leaded here anymore, was phased out at the beginning of the year... but My car runs on 102.6 Leaded race fuel and toulene (making it about 110 octane), it's going to be replaced later in the year with 100 octane Unleaded race fuel... nothing adding more toulene can't fix :)

[StereoInstaller1]

Wow, Gavin, seems like a ton of work for a "maybe". I just want you to get cracking on it so we can all "know".

My understanding with the Dbilias ITB's is that they basically add about 10% to whatever build you have...so if you were rocking 180hp on a M20 intake mani, you should get to 198, right? (YMMV, of course).

Luke

[digger]

JRowe, when I pop out the SETA pistons I'll be sure to drop you a line. This is likely to be a long process for me though, so I wouldn’t hold my breath if I were you.

Nando, I wasn’t planning on having MM do up my head. I’ve done it once before and am looking forward to doing it again, but it’s definitely worth seeing what they can do for me. And yes ITB's are on my menu as well, first item on the menu actually; I've got all the hardware I need for a custom set-up already (save for a fuel piggy-back), I just need to start cutting and welding (and endlessly fabricating until I wish I were dead).

Digger, I figured that combined with the 2mm overbore I have planned the +1mm valves would do my head some good. Is anyone around here using the +1 valves to know for sure what, if any, gains they offer?

I’m glad to hear opinion that a more aggressive cam is doable, and if the H beam rods aren’t really required I’ll save some $$ and go for the E36 M3 rods, also good to hear that a stock oil pump should suffice. Thanks for the advice so far guys, keep it coming.

It seems as though my 220 WHP goal may be unrealistic for the set-up I have in mind, but I’m looking forward to seeing what I can do with a high compression 2.8L stroker with ITB’s.

SAe30 uses bigger valves on exhaust side and makes good power but you don't know whther its the valves or something else. MM use standard valve sizes so they should be fine. Bigger valves adds valve train mass too.