Sports Valves for M52B28?

[PeterJ]

Dear Zorg,

I am thinking about playing around to optimize the power of my M52B28 a little bit more (just for fun ) without forced induction/Nitrous. I am currently considering a set of Schrick Sports Valves which are said to give better airflow & more power. Possibly stronger valve springs (Rev limiter at 7,200 rpm to match the peak power rating of the Schrick cams at 7,100rpm).... Engine is 1998 M52B28 with AFE CAI, ASC Removed, Smooth intake boot, M50 intake manifold & widened throttle body & Schrick intake camshaft ...on the exit side: Schrick Exhaust camshaft, Magna flow Sports cat & Eisenmann Sports Silencer. Other mods include Power Pulleys, Light weight flywheel & Performance clutch, lowered Final Drive Ratio & custom ECU remap
Anyone have any experience with Schrick sports valves or other brands etc? Pro's & Cons? Any significant performance benefit given my set up?

Forced Induction is out of the question & very illegal out here and not the objective. Also, do not want to drop in an S54 as it's fun trying to optimize 'Old Faithfull' M52... Also, a performance exhaust header for RHD M52B28 seems impossible to find, although there is one (untrusted option in Australia).

Then there are the valve springs ...I don't track the car and just blast it up to the 7,200 rev limit occasionally for a second or two, but otherwise take it steady ...so from what I have read, harder valve springs maybe counter productive for me most of the time as they take low end power, but allow you more power at higher RPM's ...may get the head polished etc ....no hurry & have not yet decide to do or not. Just in the 'information gathering' phase ... Would be interested to know what other performance (NA) mods are worth considering over & above what I have already

 

[z3cade]

It sounds like you have an extensive set up already if I'm honest. You would probably loose more low end torque like with the cams.

Not sure how your power delivery differs from the M but it might be worth getting it on a rolling road to see how the power is delivered now

 

[zedonist]

The idea of uprated valve springs is to prevent valve bounce at high rpm's, something you should consider with the shrick cams as the power band is moved a lot to the right, and the last thing you want is the valves opening at the wrong moment.

If you are going down the route of new valves, then get the whole head ported and gas flowed, a good flow job can get you around 10 - 20 bhp, everything you are doing is allowing more air into the engine, you need to ensure that you maintain the fuel to air ratio, or you could start to run very lean and burn out your new valves very quickly, as Liam suggests get it on a rolling road.

One of the things you should consider is actually having the cylinders enlarged and then fitting uprated injectors, this would give you quite a nice balanced modification to compliment the head work and puts you along the lines of what Alpina used to do by taking the //M from. 3.2 to 3.4. But you could possibly do it cheaper by fitting the 3.0 lump.

Whatever you do, keep us updated, as I love this sort of stuff, yes you could buy e next model up, but to me it's about making what I've got the best, good on you........

 

[PeterJ]

I do not want to alter the cylinder capacity as if I got caught (unlikely, but possible) it may be jail time for driving an illegally modified car, tax evasion, providing false info to the government, false info to insurance MOT inspector etc etc etc ...the exact cc is even written on the tax disc (square out here!) in the windscreen. I prefer to stick to mods where there is nothing saying you 'can or cannot' do it ! ...I like the idea of gas flow/ported head ... Any idea on cost range?

 

[zedonist]

It's in the region of £250 - £450 in the uk depending on spec and rebuild condition, the there is the cost of removal and refitting, circa £35 -£75 per hour depending on who is doing it. I would estimate a six hour job.

You would be best finding someone that specialises in BMW head work in order to get the best out of it, and a good place will ask you to send the inlet and exhaust manifolds so they can match the ports and Create the gaskets for you, also be mindful of a surcharge if you just buy head, as they usually want your old head in replacement.

Ideally I think you are looking at a stage 2 head ported / flowed and bigger valves, if you are doing no cylinder work then a stage 3 head will be of no benefit as you can only get so much air into your current chambers without forcing it in. In fact a decent stage 1 head with standard valves may be all you need, because I think you would need a remap on the bigger valves to get it ticking over correctly.

 

[PeterJ]

Thanks. I will do some further investigation.... maybe I will ask CA Technologies (UK) if they can help ...don't think I can get it done out here though.... I have a remap already & the guy (RUMA Tuning) can adjust it to suit ...but may have to fly him to HK again!