Cam experts

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Aleksss
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Cam experts

Post by Aleksss »

Can some cam gurus be so kind and recommand me a camshaft for my bmw rally car.

Power band 4500-8000 with a peak at 7500

24 valve inline 6, with 45mm itb
Bore 3.346
Stroke 2.952
Rod lenght 5.314
Cr 11.2
Intake valves 1.2992
Exhaust valves 1.2007
Hydralic lifters, cam pushes directly on lifter

Flow Numbers that i found on internet from a similar head.
Flow @ 28"

Intake
.050 38
.100 78
.150 118
.200 158
.250 192
.300 220
.350 232
.400 233
.450 235

Exhaust
.050 33
.100 69
.150 105
.200 143
.250 170
.300 180
.350 188
.400 189
.450 192

Thanks in advance :)
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Re: Cam experts

Post by lefty o »

try the cam king. aka jones cams. it is rumored he knows something about camshafts.
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CamKing
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Re: Cam experts

Post by CamKing »

Intake: 248@.050", .450" Lift
Exhaust: 244@.050", .450" Lift
Mike Jones
Jones Cam Designs

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jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
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Re: Cam experts

Post by Aleksss »

CamKing wrote: Mon Nov 09, 2020 12:51 pm Intake: 248@.050", .450" Lift
Exhaust: 244@.050", .450" Lift
Thank you👍 What centerline would be a good starting point ?
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Re: Cam experts

Post by CamKing »

100-102 ICL
108-110 ECL
Mike Jones
Jones Cam Designs

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jonescams@bellsouth.net
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Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
Nut124
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Re: Cam experts

Post by Nut124 »

Aleksss, is this an older BMW? Does it have variable or fixed valve timing? VVT cams usually have pretty modest durations as the VVT changes timing on the fly.

If older, I would check with Cat Cams in Europe. They make nice cams for european cars. See what their offerings are. Their website includes pretty nice spec sheets so you can compare.

http://www.catcams.com/engines/camshaft-setup.aspx#

What kind of a header do you have? Long duration cams, in excess of 290-300deg (open to open) hurt mid range. A good header with long primaries helps with bigger cams to prevent flow reversal.
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Re: Cam experts

Post by frnkeore »

I really like Cat Cams, cam cards!
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Re: Cam experts

Post by Aleksss »

Nut124 wrote: Wed Nov 11, 2020 11:18 am Aleksss, is this an older BMW? Does it have variable or fixed valve timing? VVT cams usually have pretty modest durations as the VVT changes timing on the fly.

If older, I would check with Cat Cams in Europe. They make nice cams for european cars. See what their offerings are. Their website includes pretty nice spec sheets so you can compare.

http://www.catcams.com/engines/camshaft-setup.aspx#

What kind of a header do you have? Long duration cams, in excess of 290-300deg (open to open) hurt mid range. A good header with long primaries helps with bigger cams to prevent flow reversal.
Hi, thanks for replying. Engine is the first m50b25 without vanos,
I have the s50b30 (m3) header,

I known about cat cams, and im going to buy cams from them, i just wanted to hear what camking
and other cam gurus in here would suggest,


Do You have any experience with this Engine ?
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Re: Cam experts

Post by digger »

Aleksss wrote: Wed Nov 11, 2020 7:18 pm
Nut124 wrote: Wed Nov 11, 2020 11:18 am Aleksss, is this an older BMW? Does it have variable or fixed valve timing? VVT cams usually have pretty modest durations as the VVT changes timing on the fly.

If older, I would check with Cat Cams in Europe. They make nice cams for european cars. See what their offerings are. Their website includes pretty nice spec sheets so you can compare.

http://www.catcams.com/engines/camshaft-setup.aspx#

What kind of a header do you have? Long duration cams, in excess of 290-300deg (open to open) hurt mid range. A good header with long primaries helps with bigger cams to prevent flow reversal.
Hi, thanks for replying. Engine is the first m50b25 without vanos,
I have the s50b30 (m3) header,

I known about cat cams, and im going to buy cams from them, i just wanted to hear what camking
and other cam gurus in here would suggest,


Do You have any experience with this Engine ?
whats the runner length of the intake manifold?
Aleksss
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Re: Cam experts

Post by Aleksss »

It was 380mm, but i will use pipemax when the Engine comes back together.
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Re: Cam experts

Post by Nut124 »

Aleksss, no I have no experience with your engine.

I have been working on Fiat Twincam for some 20 years and have tried quite a few cams. I'm looking to get Piper cams this winter for my project.
I have similar expectations, a bit milder perhaps, for the cam/engine: Pull strong past 7000. 7800 redline.

Below is a comparison of specs for cams I have looked at. I currently run the modest 40-80 cams. I ran the C&B 296, which was very powerful but very noisy, took it out.

The so called rallye cams seem to have less duration than all out race cams, but a lot of lift and fat lobes, lot of LATDC. This is likely to make good power w/o losing mid range torque. All out race cams, targeted at higher rpm seem to run less aggressive profiles but more duration, possibly because the valve train could not handle the rallye profile at sustained higher rpm, just my theories.

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Re: Cam experts

Post by frnkeore »

Regarding your question marks, on the Kent 102 CL. My TC, Formula Atlantic, Big Valve Hart engine ran a 102 CL. It got it's HP at 8K, tq at 6K and had a lift, in the 11mm range. I never checked duration on it, just set the CL's. Of course, it didn't have a lot of low end tq but, it was 1600cc and dynoed at 190 hp.
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Re: Cam experts

Post by Aleksss »

I got the cams now and they are
Intake 245 .050 .433 lift
Exhaust 237 .050 .433 lift


Camking You recommenden

Intake 248 @.050 100-102 centerline
Exhaust 244 @ .050 108-110 centerline

With the cams i got, would you stil use 100-102 and 108-110 centerline ? Or should i go with 102-104 and 112-114 to keep the same intake closing / exhaust opening points ?

And what is the minimum exhaust valve to piston clearence on my type of Engine ? Cat cams say 1.0mm (pref. 1.5mm.
Has anyone in here ran that tight clearence with no issues ?

Thanks
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Re: Cam experts

Post by CamKing »

start with 102 ICL and 110 ECL

I don't like running below .060" on Piston to Valve clearance.
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Re: Cam experts

Post by Nut124 »

What is the reasoning for the 100-102 ICL for these cams? Vs say 106-110?

Is the goal to keep IVC from being too late, prevent intake flow reversal? Or is overlap in itself somehow desireable?
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