in a proper 2.7 with standalone and the car was on the rollers being mapped?
just wondering really if anyone has done it, seems to me most peak before 6000rpm
i'm just wondering!
284/272 cam can HP be had over 6000 RPM?
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Ant
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Good Q dude !
I've noticed this trend too, we need some dyno sheets of cammed 2-5 and 2-7 with spec to compare.
Sal, where are the prints for the Alpina dude ??
I've noticed this trend too, we need some dyno sheets of cammed 2-5 and 2-7 with spec to compare.
Sal, where are the prints for the Alpina dude ??
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Just in case it helps! My mildly tuned high comp 2.7:
http://img85.imageshack.us/my.php?image ... quewd0.jpg
http://img85.imageshack.us/my.php?image ... quewd0.jpg
This is a very good question.
My standard C2 2.7 engine had standalone fitted at the same time as the Siliver 4 door C2 2.7 which has a 284/272 cam.
At the time neither car had a 6 branch and used the same exhaust system and of course the same set of rollers.
My car made 195 bhp and 200 lb.ft torque. Peak power was achieved at exactly 5800rpm, exactly what Alpina claim it to be at.
The 284/272's C2 engine made peak power at 6500rpm. Peak power was 208 bhp. the 20bhp difference is not the cam alone because this engine has been rebuilt with total seal rings whereas mine had around 120k on it and was standard.
The silver C2 has had a 6 branch fitted since and been remapped to suit, peak power still sits around 6500rpm but went up to 216 bhp and the power really starts coming in at 3000rpm after which it is truly mental.
I fitted the newer style BTB manifold to it last week and it has made a significant difference.
Simon, I'll bring the C2 again and you drive it this time. You'll know straight away if the cam suits your driving style.
Sal
My standard C2 2.7 engine had standalone fitted at the same time as the Siliver 4 door C2 2.7 which has a 284/272 cam.
At the time neither car had a 6 branch and used the same exhaust system and of course the same set of rollers.
My car made 195 bhp and 200 lb.ft torque. Peak power was achieved at exactly 5800rpm, exactly what Alpina claim it to be at.
The 284/272's C2 engine made peak power at 6500rpm. Peak power was 208 bhp. the 20bhp difference is not the cam alone because this engine has been rebuilt with total seal rings whereas mine had around 120k on it and was standard.
The silver C2 has had a 6 branch fitted since and been remapped to suit, peak power still sits around 6500rpm but went up to 216 bhp and the power really starts coming in at 3000rpm after which it is truly mental.
I fitted the newer style BTB manifold to it last week and it has made a significant difference.
Simon, I'll bring the C2 again and you drive it this time. You'll know straight away if the cam suits your driving style.
Sal
In addition to this Bexleys 2.7 with a 288/288 cam made peak power at 7000 rpm with around 232 bhp. Stupidly high compression, very well ported head.
Also the silver C2's power does not drop of dramatically after 6500rpm until after 7000rpm. Limiter was therefore put in at 6900 rpm.
Also the silver C2's power does not drop of dramatically after 6500rpm until after 7000rpm. Limiter was therefore put in at 6900 rpm.
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professormatt
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my 2.7 has 288/288 cam the rev limit is set to 7500rpm,sh*$t off a shovel!
well untill the head cracked!
the big boys in sewden weld them for a reason!!!!
well untill the head cracked!
the big boys in sewden weld them for a reason!!!!
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Simon13
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Griffen motorsport welded them up for this reason also! it's a shame they are no longer trading
i think the cam stated is the best of both worlds, when my 2.7 is rebuilt i don't want to loss too much low end grunt like with a 288/288 or higher would. Oh not sure! A 290 kkk cam which make it shift though. I just want a good allrounder i think. It's a long way off anyway!
See if that silver C2 has peak power at 6500rpm i'd want the limiter to be at 6700rpm no? M20's don't like reving that high with out extra work being done to stop them going bang
i think the cam stated is the best of both worlds, when my 2.7 is rebuilt i don't want to loss too much low end grunt like with a 288/288 or higher would. Oh not sure! A 290 kkk cam which make it shift though. I just want a good allrounder i think. It's a long way off anyway!
See if that silver C2 has peak power at 6500rpm i'd want the limiter to be at 6700rpm no? M20's don't like reving that high with out extra work being done to stop them going bang
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Turbo-Brown
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You gonna plump for ITBs then Simon? Be a shame not to 
What static compression you building it to also, and any idea what the dynamic becomes then?
What static compression you building it to also, and any idea what the dynamic becomes then?
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Simon13
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thing is t-brown, i'm worried if i save and bought itb's would it detract a little from how the original engine was or improve on it overall. I've understood it to move aload of power up the top and adds a good few HP's too.
And would someone want to buy it off me if the engine was a little modded! but it is my car i suppose
your last sentence lost me there! compression is around 10.2:1 as standard, i doubt u would want it any higher on a road car?
dynamic?!
And would someone want to buy it off me if the engine was a little modded! but it is my car i suppose
your last sentence lost me there! compression is around 10.2:1 as standard, i doubt u would want it any higher on a road car?
dynamic?!
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Turbo-Brown
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No idea what the idle would be like with the cam you mentioned, but I can't imagine it'd be great, especially if it's designed to make power all the way oop there. Would imagine the low end would be a bit wooly too what with air darting about all over the place in the standard plenum.
That said having lots of cylinders should help mask the problem.
ITBs shouldn't necessarily move the power, although ithey do give you the chance to play with your tuned lengths as to further maximise your output and that can move the power about.
The static CR is what's normally quoted all over the shop and is calculated by adding the clearance volume of the chamber to the swept volume of the cylinder and then dividing by the clearance vol so if,
Clearance 'C'=10cc
Cyl Vol 'V'=100cc
CR=(10+100)/10=11:1
However, the more lairy the cam you run, the less air gets trapped in the cylinder as things like the inlet valve being open on the compression stroke lets some air out, and some just passes straight through on overlap which isn't great for emissions of course (or economy).
You can draw out, to scale, everything you've got in terms of stroke, conrod length and the effective (after the rockers have added their 2p) valve timing (yes the length of the conrod and throw of the crank effect the compression ratio).
When you draw it all out, you see that the valve closing points all subtract from the effective swept volume of the engine which in turn reduces the compression ratio. The lairier the cam, the lower the dynamic CR as the valves being open for ages lets air out that should be being compressed.
This is why you see race engines with seemingly whopping compression ratios, they're upping the static CR to compensate for the loss of dynamic brought about by fitting large duration/high overlap cams.
Having drawn it all out, you can have a fiddle with the angle of the cam and see what effect that has.
Then there's the 'on cam' bit which is where instead of bouncing out of the cylinder, the pulsing air in the inlet tract actively forces it's way in, kinda like free supercharging, and that's where being able to play with your tuned lengths would come into play.
Problem is finding an ITB setup that would let you adjust the tract lengths as Dbilas sure as hell can't and the only other two manifolds I've seen either point the TBs straight at the servo or straight up at the underside of the bonnet
That said having lots of cylinders should help mask the problem.
ITBs shouldn't necessarily move the power, although ithey do give you the chance to play with your tuned lengths as to further maximise your output and that can move the power about.
The static CR is what's normally quoted all over the shop and is calculated by adding the clearance volume of the chamber to the swept volume of the cylinder and then dividing by the clearance vol so if,
Clearance 'C'=10cc
Cyl Vol 'V'=100cc
CR=(10+100)/10=11:1
However, the more lairy the cam you run, the less air gets trapped in the cylinder as things like the inlet valve being open on the compression stroke lets some air out, and some just passes straight through on overlap which isn't great for emissions of course (or economy).
You can draw out, to scale, everything you've got in terms of stroke, conrod length and the effective (after the rockers have added their 2p) valve timing (yes the length of the conrod and throw of the crank effect the compression ratio).
When you draw it all out, you see that the valve closing points all subtract from the effective swept volume of the engine which in turn reduces the compression ratio. The lairier the cam, the lower the dynamic CR as the valves being open for ages lets air out that should be being compressed.
This is why you see race engines with seemingly whopping compression ratios, they're upping the static CR to compensate for the loss of dynamic brought about by fitting large duration/high overlap cams.
Having drawn it all out, you can have a fiddle with the angle of the cam and see what effect that has.
Then there's the 'on cam' bit which is where instead of bouncing out of the cylinder, the pulsing air in the inlet tract actively forces it's way in, kinda like free supercharging, and that's where being able to play with your tuned lengths would come into play.
Problem is finding an ITB setup that would let you adjust the tract lengths as Dbilas sure as hell can't and the only other two manifolds I've seen either point the TBs straight at the servo or straight up at the underside of the bonnet
Simon13 wrote:Griffen motorsport welded them up for this reason also! it's a shame they are no longer trading
i think the cam stated is the best of both worlds, when my 2.7 is rebuilt i don't want to loss too much low end grunt like with a 288/288 or higher would. Oh not sure! A 290 kkk cam which make it shift though. I just want a good allrounder i think. It's a long way off anyway!
See if that silver C2 has peak power at 6500rpm i'd want the limiter to be at 6700rpm no? M20's don't like reving that high with out extra work being done to stop them going bang
Don't get the 288/288, I have that as you know. You thought my Sport had an idle problem with my car but it was just the cam. Don't want people taking the p*ss out of your car saying it has issues idleing now do we?
Seriously, top end power is awesome, it sounds like the car wants to take-off like a jet!
284/272 will probably be best for what you're looking for fella.
Regards, BJ.
Seriously, top end power is awesome, it sounds like the car wants to take-off like a jet!
284/272 will probably be best for what you're looking for fella.
Regards, BJ.
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Simon13
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Jo that was a joke to gee u up about the ICV being knackered
The alpina idles lumpy as it is and thats with a alpina cam, but not 100% sure it is the alpina cam
DADDG- who are they trading as now?!
The alpina idles lumpy as it is and thats with a alpina cam, but not 100% sure it is the alpina cam
DADDG- who are they trading as now?!
Simon,
both my car and the silver C2 had 100% smooth idle when they had the origional camshaft.
Even with the 284/272 cam the idle is only very slightly lumpy.
Going from Alpina cam to 284 does lose you some bottom end. It's still very good but it does feel a little whooly.
Your comments on rev limit are relevant. I will probably lower it to 6700rpm.
If we meet again when I have the C2 you are more than welcome to drive it (not just down the road but for a good 20 mins) and I am sure you'll be able to make a decision. For me atleast I find it to give the best of both worlds.
Sal
both my car and the silver C2 had 100% smooth idle when they had the origional camshaft.
Even with the 284/272 cam the idle is only very slightly lumpy.
Going from Alpina cam to 284 does lose you some bottom end. It's still very good but it does feel a little whooly.
Your comments on rev limit are relevant. I will probably lower it to 6700rpm.
If we meet again when I have the C2 you are more than welcome to drive it (not just down the road but for a good 20 mins) and I am sure you'll be able to make a decision. For me atleast I find it to give the best of both worlds.
Sal
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Ant
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do it si, it actually drives sweet on part throttle now too, much improved over the previous all or nothing, amazing what you can achieve with some time, a laptop and WB02
I have both 2.7 blocks back from the machine shop now, will post some pix later, V nice too
I have both 2.7 blocks back from the machine shop now, will post some pix later, V nice too
Product Development and Endurance for Delphi.
Original performance chips, original works not unlicensed copies Email FTW
Original performance chips, original works not unlicensed copies
Email FTWSince you have a 2.7 Si, I don't think losing some of the bottom end will effect you that much. 284/272 will sort you right out.
Oh & you know about the high performance valve springs that you may need to invest in?
Regards, BJ.
Oh & you know about the high performance valve springs that you may need to invest in?
Regards, BJ.
Ah Swindon crew! I know Lydiard, they are still based there then.DADDG wrote:I've Used them when needed
Where in Swindon are ya DADDG?
Lets av it then Ant, i wanna see, can i seeAnt wrote:do it si, it actually drives sweet on part throttle now too, much improved over the previous all or nothing, amazing what you can achieve with some time, a laptop and WB02
I have both 2.7 blocks back from the machine shop now, will post some pix later, V nice too
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handpaper
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Talking to the boys at http://www.qep.co.uk can be an education, too. They quote £350 delivered for any catcams M20 cam + a set of new rockers.
Catcams 283/283 is apparently the wildest you can fit without uprating valve springs or machining piston tops - I've heard that the stock Motronic ECU can be remapped to handle this, can Ant or anyone else confirm this?
Catcams 283/283 is apparently the wildest you can fit without uprating valve springs or machining piston tops - I've heard that the stock Motronic ECU can be remapped to handle this, can Ant or anyone else confirm this?
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handpaper
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Nice, but whose 288? Cams from different manufacturers will vary; lift and duration both need watching.Jhonno wrote:288 works without pocketing the pistons.. anything over that and your looking at contact issues
MoT for non-cat cars doesn't seem to include an emissions test anymoreSimon13 wrote:288/288 = emissions problems
I'd be more worried about getting the thing to idle properly without fitting ITBs. Then again, it's a marvellous excuse
