S54 Stroker build

[8 Coupe]

Flywheel, clutch and pressure plate are where the rotational inertia is in the engine.

My rebuilt engine is now in the car & I have a couple of pics showing the low rotational mass of the JB Racing Ultra Light Flywheel & Clutch kit - very well designed & manufactured kit but only suitable for use on the track.

[Jhinz03]

Flywheel, clutch and pressure plate are where the rotational inertia is in the engine

youd be nuts to choose 1700 rods to gain nothing material when you can do Actual performance mods.

Oh I wasn't changing the rods to try to gain performance. I was changing the rods as part of building out the engine due to it being nearly 2 decades old and likely having over 150k miles on it. I was going to go to a forged H-beam rod anyways, and these were the same price as the standard rod. I figured a lighter rod might reduce parasitic loss and maybe help it rev a little quicker. I'm hesitant to lighten the flywheel since I'm worried about making shifting in Miami rush hour a pain. Clutch is on the build list.

[digger]

What would be the low hanging fruit for reducing rotating weight? I'm likely swapping the rods anyways if I'm already opening the engine, so that seemed a logical choice. I will eventually start trying to lighten the car as much as reasonable. I wouldn't open the engine JUST to swap in lightweight rods, but if I'm in there, I figured why not. Eventually looking at things like a CF driveshaft, I have budgeted for forged wheels that'll drop 55lbs and a lightweight battery whenever the stock battery needs replacement.

Flywheel, clutch and pressure plate are where the rotational inertia is in the engine

youd be nuts to choose 1700 rods to gain nothing material when you can do Actual performance mods.

[mrgizmo04]

3.5L Stroker

https://youtu.be/A0GiUoGkf0k

Sent from my SM-G950U using Tapatalk

[Jhinz03]

What would be the low hanging fruit for reducing rotating weight? I'm likely swapping the rods anyways if I'm already opening the engine, so that seemed a logical choice. I will eventually start trying to lighten the car as much as reasonable. I wouldn't open the engine JUST to swap in lightweight rods, but if I'm in there, I figured why not. Eventually looking at things like a CF driveshaft, I have budgeted for forged wheels that'll drop 55lbs and a lightweight battery whenever the stock battery needs replacement.

[digger]

If I end up stroking it, it would be to gain some lower end torque. I'm less concerned with getting a big number at 8300 than general driveabilty and all around fun experience. It's going to be a daily more than anything. I have a short, relatively traffic-free commute, but the wife and I also like to go for a drive sometimes at night (which is why I'm actually looking for the drop top). If I just wanted a huge HP number, I'd slap a custom turbo kit on it and call it a day. The fun factor is also part of the reason for the velocity stacks over a CAI. I just like the sound they make and the feel of the throttle response. I think I may just grab some lightweight Carillo rods since they support 400whp and I dont plan on going higher than that and some 12.5:1 pistons. Also debating 14mm lift on the cams and having the pistons recessed a little.

Am I wrong in thinking using lighter internals would reduce drivetrain loss to the whp?

i wouldn't destroke it then as youd only do that to improve the bottom end reliability/durability at higher rpm.
Lighter rods wont do much of anything for dyno performance. if you want a lighter rotating weight then rods are not the low hanging fruit.
Its easy to to spec the pistons to suit cams in any case. i'd get a Mahle MS 4032 type alloy.

[Jhinz03]

If you destroked you’d just run a shorter final drive to make up the difference. The engine will just be a bunch busier in that it will always spinning faster at a given road speed. Personally I’d rather have the stroke for a bit more effortless / accessible performance.

the power is always in the top end of the engine the bottom end just determined the rpm where it happens (scales peak hp rpm up or down)

it’s amazing how many think stroking an engine makes more peak power inherently as it’s just completely wrong to assume that. It’s not to say you won’t get gains but it comes down to what’s limiting power in the first place

If I end up stroking it, it would be to gain some lower end torque. I'm less concerned with getting a big number at 8300 than general driveabilty and all around fun experience. It's going to be a daily more than anything. I have a short, relatively traffic-free commute, but the wife and I also like to go for a drive sometimes at night (which is why I'm actually looking for the drop top). If I just wanted a huge HP number, I'd slap a custom turbo kit on it and call it a day. The fun factor is also part of the reason for the velocity stacks over a CAI. I just like the sound they make and the feel of the throttle response. I think I may just grab some lightweight Carillo rods since they support 400whp and I dont plan on going higher than that and some 12.5:1 pistons. Also debating 14mm lift on the cams and having the pistons recessed a little.

Am I wrong in thinking using lighter internals would reduce drivetrain loss to the whp?

[digger]

If you destroked you’d just run a shorter final drive to make up the difference. The engine will just be a bunch busier in that it will always spinning faster at a given road speed. Personally I’d rather have the stroke for a bit more effortless / accessible performance.

the power is always in the top end of the engine the bottom end just determined the rpm where it happens (scales peak hp rpm up or down)

it’s amazing how many think stroking an engine makes more peak power inherently as it’s just completely wrong to assume that. It’s not to say you won’t get gains but it comes down to what’s limiting power in the first place

[Jhinz03]

I will most likely be keeping VANOS, since it's mostly going to be a daily driver with VERY occasional track use. The more I ready, I think 288/280 is probably closer to where I want to be. The idea of stroking it was mostly due to the fact that I was likely going to have to replace the rod bearings and wanted to increase the compression, so I figured I'd do it while I was in there. Destroking honestly doesn't sound like a terrible idea, except I feel like I'd be losing more torque then I'd like. There are a couple fairly highly regarded BMW tuners locally in Miami, so I doubt it'd be too difficult to find someone to get it dialed in.

[digger]

I'd probably run flex if I run anything at all but haven't really decided. Would honestly prefer regular 93 if I thought I could get away with it.

I'm definitely open to finding a local shop to port the head, but the Lang seems to be a good option and I've heard good things about them.

The PS Designs stack kit has a CF heat shield and some nice scoops to route air in. Im also going to be venting the hood to help with temp control.

What cams would you recommend? 288/280?

Schrick big lift 288/280

there are some great Honda shops that might be interested some of them extremely competent people working there. Don’t limit yourself to local

lots of hot contaminated air still gets ingested

[8 Coupe]

Jhinz03, are you intending to use a VANOS Delete Kit (Achilles or VAC) or retain VANOS operation? If the Cams are too long a duration, combined with greater valve depression then you run the risk of contact between the valves and pistons. You can reduce the amount of VANOS movement electronically to prevent this (if you are using an aftermarket ECU) but there's always a risk that it may have a glitch so you really need to mechanically limit it, especially on the intake cam. I'm using Cat Cams 296/288 which are considered to be at the upper limit to use with VANOS although 288/280 is considered optimum for street use.

On the subject of installing a stroker kit, the guy who has built my engine, previously built a 3.5L stroked S54 and he recently said that he won't do another stroked one. He said that the gains are not very great considering the expense and the engine doesn't rev as freely with the power shifted to a lower rev range. Another guy, who races an E46 M3 de-stroked it so that he can compete in sub 3.0L events, said that the engine response is much better and he's able to get the power down better when coming out of corners. Apart from bragging rights, stroking an S54 does not necessarily make it a better engine in terms of "using" the power.

[Jhinz03]

what is the engine to be used for? are you going to run e85 or flex? if the former then youd want a bit more than 12.5:1

honestly i'd probably avoid the usual suspects and their stage 3.1415 heads (alot of the description is verbatim from each other lol) and seek out the services of specialist porter.

honestly youd be better off with a CSL style airbox, when the hood is closed routing cold air is critical for performnace and knock control

i think those cams will probably be overkill and hurt the broadness of the powerband more than it helps the topend

I'd probably run flex if I run anything at all but haven't really decided. Would honestly prefer regular 93 if I thought I could get away with it.

I'm definitely open to finding a local shop to port the head, but the Lang seems to be a good option and I've heard good things about them.

The PS Designs stack kit has a CF heat shield and some nice scoops to route air in. Im also going to be venting the hood to help with temp control.

What cams would you recommend? 288/280?

[digger]

Following this post because I am planning on something VERY similar early next year. My current plan has me going with the Lang Racing stroker kit with the 97mm stroke and keeping the 87mm bore, along with Lang's stage 3 head and 304/296 cams. Also planning to run a full SuperSprint exhaust including the stepped header and race muffler with test pipes and going with PSDesigns's velocity stacks. I haven't decided on the DME and whether I want to use E85 (there are two stations within a mile of home that sell it), but Active Autowerke isn't far and they have a great reputation locally (and online it seems) for tuning this engine. They did a similar VAC stroker kit build a few years ago and made 370rwhp without too much more than the stroker kit and tune. Also likely going to 12.5:1. Project will likely be done in several stages as money comes in, with the stroker kit going in last. Any thoughts or suggestions would be greatly appreciated as this will be my first BMW project and first project of this scale.

what is the engine to be used for? are you going to run e85 or flex? if the former then youd want a bit more than 12.5:1

honestly i'd probably avoid the usual suspects and their stage 3.1415 heads (alot of the description is verbatim from each other lol) and seek out the services of specialist porter.

honestly youd be better off with a CSL style airbox, when the hood is closed routing cold air is critical for performnace and knock control

i think those cams will probably be overkill and hurt the broadness of the powerband more than it helps the topend

[Jhinz03]

Following this post because I am planning on something VERY similar early next year. My current plan has me going with the Lang Racing stroker kit with the 97mm stroke and keeping the 87mm bore, along with Lang's stage 3 head and 304/296 cams. Also planning to run a full SuperSprint exhaust including the stepped header and race muffler with test pipes and going with PSDesigns's velocity stacks. I haven't decided on the DME and whether I want to use E85 (there are two stations within a mile of home that sell it), but Active Autowerke isn't far and they have a great reputation locally (and online it seems) for tuning this engine. They did a similar VAC stroker kit build a few years ago and made 370rwhp without too much more than the stroker kit and tune. Also likely going to 12.5:1. Project will likely be done in several stages as money comes in, with the stroker kit going in last. Any thoughts or suggestions would be greatly appreciated as this will be my first BMW project and first project of this scale.

[8 Coupe]

What clutch did you choose with your lightweight flywheel?

I bought the JB Racing Ultra Light Race Flywheel/Clutch kit. The clutch is only 140mm (5.5") diameter with two plates. This design will significantly reduce the rotating mass compared to a conventional flywheel and clutch.

I believe that the plate surfaces are scintered iron which don't "slip" well thus, it will make manoeuvring in tight spaces a bit more difficult, as well as issues trying to drive the car onto the trailer.

http://www.jbracing.com/flywheel-bmwul1.php