E30 Zone

hi i was just wondering what camshafts people recamend. I am re building a 325i engine and want lots of bottom end power. i have had a little look and cant see allot on low end camshafts every thing is for top end so i think i might go for a 288 degree camshaft. the wright up on the 288 degree cams say slight loss in low-end torque so im thinking that's the best im going to get. What set ups are some of you running and what bhp are you getting.

Reggid should chime in here, he is pretty knowledgable on camshafts.

Your bottom end power will depend on your compression ratio.... Stock compression ratio is 8.8 so a 288 cam will be a dog on a stock motor.

I went with a DBilas 276 cam for better low end power, even though my comp will be up around 9.8.

Yea just got an email from the bloke who will be doing my cam shaft and he recamends a 276 degree cam shaft. So I think I might go for that.

The duration alone wont tell you enough information. youll need the LSA so you can workout the opening and closing events. Basically you want the intake closing point to be as early as possible for torque. this will show as high cranking compression which sort of correlates to dynamic compression. The details on the rebuild are a bit sketchy as are your goals but assuming standard rebuild (no stroking / boring) I would look to bump the CR up via skimming the head or similar means, use 98RON with an adjsutable cam gear and custom tuning with a stock to 270ish cam. Stay away from catcams.

As with all cams usually it is a compromise as to where you want the torque to be improved. With a cam change by itslef usually you give up some from one part of the operating range to give it to another

yeah what he said....

reggid wrote:The duration alone wont tell you enough information. youll need the LSA so you can workout the opening and closing events. Basically you want the intake closing point to be as early as possible for torque. this will show as high cranking compression which sort of correlates to dynamic compression. The details on the rebuild are a bit sketchy as are your goals but assuming standard rebuild (no stroking / boring) I would look to bump the CR up via skimming the head or similar means, use 98RON with an adjsutable cam gear and custom tuning with a stock to 270ish cam. Stay away from catcams.

As with all cams usually it is a compromise as to where you want the torque to be improved. With a cam change by itslef usually you give up some from one part of the operating range to give it to another

cheers for that. I will be using http://www.autosprint.co.uk/ unless any one has a good reson not to. I have looked for some cams but there all abit pricey.

christophsbmw wrote:

reggid wrote:The duration alone wont tell you enough information. youll need the LSA so you can workout the opening and closing events. Basically you want the intake closing point to be as early as possible for torque. this will show as high cranking compression which sort of correlates to dynamic compression. The details on the rebuild are a bit sketchy as are your goals but assuming standard rebuild (no stroking / boring) I would look to bump the CR up via skimming the head or similar means, use 98RON with an adjsutable cam gear and custom tuning with a stock to 270ish cam. Stay away from catcams.

As with all cams usually it is a compromise as to where you want the torque to be improved. With a cam change by itslef usually you give up some from one part of the operating range to give it to another

cheers for that. I will be using http://www.autosprint.co.uk/ unless any one has a good reson not to. I have looked for some cams but there all abit pricey.

ask them for a camcard there are not enough specs on the website to know what you will get

reggid wrote:Stay away from catcams.

Why?

reggid wrote:Stay away from catcams.

nothing wrong with catcams ive got one in my turbo bloody spot on if you ask me

A high lift camshaft is always going to lose low end torque. This can be mitigated by raising the compression ratio and suitable remapping/chip.

Catcams are OK. I saw an E30 325i cab lat summer have a 272/272 catcam fitted AND a suitable to chip to suit the new cam.

The stock cam will give strong low end torque but less power than a high lift cam.

If you want more low end power and more power up top - just a cam and a chip won't do this.

chu346 wrote:

reggid wrote:Stay away from catcams.

Why?

he wants lowend torque, catcams are for midrange and topend (what they are designed to do). I have one and have seen dyno of atleast 3 others and they lose more lowend than schricks but make more midrange and topend this is why i dont think they are the cam for the OP.

toby wrote:A high lift camshaft is always going to lose low end torque. This can be mitigated by raising the compression ratio and suitable remapping/chip.

Catcams are OK. I saw an E30 325i cab lat summer have a 272/272 catcam fitted AND a suitable to chip to suit the new cam.

The stock cam will give strong low end torque but less power than a high lift cam.

If you want more low end power and more power up top - just a cam and a chip won't do this.

despite what people think increasing lift alone wont lose lowend it is the changing of the valve events that does it. Because of the limit to how fast you can open a valve in a controlled manner there gets a point that you need more duration to allow the valve to lift really high. I have seen cams that lift upto 11.5mm but have little more duration than stock so these wont lose lowend

to add to the above a standard head doesn't really gain a lot by lifting the valves past 10.5mm lift, The flow curve is pretty flat there so keeping the valve at 10.5mm lift for longer will be nearly the same as lifting higher.

a cam with a similar duration but faster opening rate and longer dwell would be the best bet.

HairyScreech wrote:to add to the above a standard head doesn't really gain a lot by lifting the valves past 10.5mm lift, The flow curve is pretty flat there so keeping the valve at 10.5mm lift for longer will be nearly the same as lifting higher.

a cam with a similar duration but faster opening rate and longer dwell would be the best bet.

i just recall that i havent posted the cams i recently plotted out

christophsbmw wrote: I am re building a 325i engine and want lots of bottom end power.

Then one of the first things you need is more displacement via a longer stroke. Find a scrap M52 2.8 engine, and use the crankshaft - you should get one for around £100. In terms of power per £, it's one of the best mods you can make. You can use standard 325i pistons allied to 320i/525e conrods and avoid block decking/vernier pulleys etc.
With a decent camshaft and a proper remap, it will go extremely well.

Andyboy wrote:

christophsbmw wrote: I am re building a 325i engine and want lots of bottom end power.

Then one of the first things you need is more displacement via a longer stroke. Find a scrap M52 2.8 engine, and use the crankshaft - you should get one for around £100. In terms of power per £, it's one of the best mods you can make. You can use standard 325i pistons allied to 320i/525e conrods and avoid block decking/vernier pulleys etc.
With a decent camshaft and a proper remap, it will go extremely well.

to the OP if it is an option do this

reggid wrote:

Andyboy wrote:

christophsbmw wrote: I am re building a 325i engine and want lots of bottom end power.

Then one of the first things you need is more displacement via a longer stroke. Find a scrap M52 2.8 engine, and use the crankshaft - you should get one for around £100. In terms of power per £, it's one of the best mods you can make. You can use standard 325i pistons allied to 320i/525e conrods and avoid block decking/vernier pulleys etc.
With a decent camshaft and a proper remap, it will go extremely well.

to the OP if it is an option do this

Any more info on this mod sounds intresting. I have a 325i engine ready to strip a 320 engine in the car I can use bits from. So all I would need is a m52 328 crank use the 320 conrods and 325 pistons ?

Also I'm unsure what you mean by block decking. When I'm home fr
Work I'll have a google on this shit and see what I find.

I've used cat cams before (currently got one in my engine) while there is/maybe a slight lose low down there is a noticable "kick" higher up the rev range.

also autosprint should be able to regrind your current cam to 274 - 276dg for £145.

Have a look on the wiki for 2.8 build info - it's all there.

steve_k wrote:I've used cat cams before (currently got one in my engine) while there is/maybe a slight lose low down there is a noticable "kick" higher up the rev range.

also autosprint should be able to regrind your current cam to 274 - 276dg for £145.

yea thats what they told me. i will be going for that.

christophsbmw wrote:Also I'm unsure what you mean by block decking. When I'm home fr
Work I'll have a google on this shit and see what I find.

You need the standard 325i block, standard 320i or 525e 130mm (centre to centre) con rods and a pre 9/98 328i or 528i/728i crank.
If you use a 2.7 525e crank, the pistons are 3mm short of the top of the block which is why the block needs 3mm taking of the top (decking). The 2.8 crank has a 3mm longer stroke, 84mm-v-81mm. Therefore the pistons come to the top of the block perfectly. The block top face will always need a 5 thou clean up skim but that's it.
Even with the 84mm stroke, the con rod angularity is within limits and you don't need to fart about with verniers. A full on engine build would mean checking the cam timing with a protractor and a dial gauge, and a vernier pulley to get it absolutely 101% perfect but that's something you can do once the engine is in the car and fully run in. I don't know about Cat cams, but Schrick stuff is pretty accurate.

Even with the standard BMW camshaft, a well set up 2.8 goes really well. The extra displacement, longer stroke and resulting higher compression will need a proper remap but it's well worth it.

FWIW, Alpina used a 268/268 cam in their Alpina C2 2.5, which was based on the 325i.

Andyboy wrote:

christophsbmw wrote:Also I'm unsure what you mean by block decking. When I'm home fr
Work I'll have a google on this shit and see what I find.

You need the standard 325i block, standard 320i or 525e 130mm (centre to centre) con rods and a pre 9/98 328i or 528i/728i crank.
If you use a 2.7 525e crank, the pistons are 3mm short of the top of the block which is why the block needs 3mm taking of the top (decking). The 2.8 crank has a 3mm longer stroke, 84mm-v-81mm. Therefore the pistons come to the top of the block perfectly. The block top face will always need a 5 thou clean up skim but that's it.
Even with the 84mm stroke, the con rod angularity is within limits and you don't need to fart about with verniers. A full on engine build would mean checking the cam timing with a protractor and a dial gauge, and a vernier pulley to get it absolutely 101% perfect but that's something you can do once the engine is in the car and fully run in. I don't know about Cat cams, but Schrick stuff is pretty accurate.

Even with the standard BMW camshaft, a well set up 2.8 goes really well. The extra displacement, longer stroke and resulting higher compression will need a proper remap but it's well worth it.

If you take a B25 and add eta crank and nothing else then the 6mm longer stroke makes the pistons protrude 3mm higher up than they were. If you then swap in 5mm shorter rods the piston is 2mm lower in the block compared to B25.

If you take a B25 and add B28 crank and nothing else then the 9mm longer stroke makes the pistons protrude 4.5mm higher up than they were. If you then swap in 5mm shorter rods the piston is 0.5mm lower in the block compared to B25.

The B28 also will have a higher CR if the piston position at TDC is maintained.