Technical High lift camshafts
- Thread starter Marti155
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Technical High lift camshafts
Well, there's the Punto 75 cam -- 2nd hand, very cheap, works well. There are a stack of cams made by C & B in Italy (good cams, not cheap), and a few made in the UK. Best ask Oldschool (GSR) for advice on these.
All depends what you want to do.
All depends what you want to do.
It wont. its made for these engines
im running the whole punto 75 engine on the stock ecu with not trouble at all (having trouble with the aftermarket chip tho )things ive noticed with the p75 cam is...
- Alot less bottom end! {In very slow moving traffic I used to be able to leave the engine at idle and slip the clutch to pull me along. now it just stubles and hops (imagine it would be even worse on a 1.1). this I expected}
- the power comes in by the bucket load at around 5k :slayer:
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Sounds like you have problems. I've used P75 cams in 1.2 & 1.1 SPIs with a 40mm TB and a GSR F1i induction kit, the latter having a large bore exhaust. My current 1108cc MPI also runs a P75 cam but only has an induction kit. All were remapped to some extent.
All 3 easily pull away in 2nd at 1000~1250 rpm & the 1.1 SPI had 195/45R15 rubber. All 3 also were fine at idle in 1st gear.
The 1.2 got going a little above 2800 and tailled off after 6300ish
The 1.1 SPI started to pull hard from around 3250 till the 6600 to 6750 mark
The 1.1 MPI kicked in around 3000 rpm and becomes breathless around 6200, it feels eager like it wants to rev on so maybe the exhaust and/or throttle body is restricting it.
All 3 easily pull away in 2nd at 1000~1250 rpm & the 1.1 SPI had 195/45R15 rubber. All 3 also were fine at idle in 1st gear.
The 1.2 got going a little above 2800 and tailled off after 6300ish
The 1.1 SPI started to pull hard from around 3250 till the 6600 to 6750 mark
The 1.1 MPI kicked in around 3000 rpm and becomes breathless around 6200, it feels eager like it wants to rev on so maybe the exhaust and/or throttle body is restricting it.
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P75 cam should pretty much just work. You need to check the valve clearances and will probably have to do the old shim shuffle and buy a new shim or two, but it really is no big deal doing that.
While a re-map will give you a bit more (as would some RR time with a vernier pulley) best to leave that until you've finalised the induction and exhaust.
They are really nice cams: the car should be pretty tractable still, but with much more oomph. Check the bearing surfaces on the cam: you're just looking for smoothness, rather than gauging caused by some klutz not changing the oil and filter often enough.
While a re-map will give you a bit more (as would some RR time with a vernier pulley) best to leave that until you've finalised the induction and exhaust.
They are really nice cams: the car should be pretty tractable still, but with much more oomph. Check the bearing surfaces on the cam: you're just looking for smoothness, rather than gauging caused by some klutz not changing the oil and filter often enough.
should of mentioned im using the punto 75 head and manifold. with spi. the porting on the punto 75 head is somewhat larger then the other heads so that might be the reason.
dont get my wrong it will pull just not as much as the stock engine.
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You're using a P75 manifold wet? That's gonna cause problems at low rpm, well any low airflow conditions really.
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Nah
I think my best move will be to fit the punto 75 cam with a larger throttle body i was going to port and polish the standard block but just getting punto 75 cylinder head might be a better idea is there much work to get the 75 head to fit on the 1108cc block or is it a direct swap
Direct fit mate.
Well the head to block is! theres some work involved in fitting the spi manifold to the head as the top four studs are higher! you need to make 3 plates to bolt the top down and do a little grinding in the manifold to match the ports (the mpi ports are taller due to the injectors)
only about a hours work with a rotory tool. have a look on my blog (v link in sig v)
I recon its worth it as it saves farting about with shims
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And if you can get the throttle body with the head you can make a larger throttle body from that and save a few quid
Well the head to block is! theres some work involved in fitting the spi manifold to the head as the top four studs are higher! you need to make 3 plates to bolt the top down and do a little grinding in the manifold to match the ports (the mpi ports are taller due to the injectors)
only about a hours work with a rotory tool. have a look on my blog (v link in sig v)
I recon its worth it as it saves farting about with shims
edit:
And if you can get the throttle body with the head you can make a larger throttle body from that and save a few quid
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Are you nuts?
1. I'd point out that what you've done clearly doesn't work.
2. Doing the shims is easier, quicker and cheaper than bodging an SPI mani onto an MPI head. It's a couple of hours work, nothing more. You need nothing more than a set of feeler guages and a torque wrench (a calculator helps).
3. Checking the valve clearances (and fitting different shims) should be a routine (albeit infrequent) part of maintenance.
fitting a spi manifold to a mpi does work... theres no reason it wont!
If the engine I had bought had done alot of miles then maybe I would of just used my 1.1 head, but as the p75 engine i got had only done 9k and the clearances where all perfect, There is no reason to **** about with it.
I have a habbit of checking clearances due to owning single cylinder 4strokes which need doing at least ever thousand miles! so I check them every time I do a oil change.
craigb244 said:
I rest my case. Seems that something -- and I'd guess the match of the SPI inlet mani (the Uno 45 one is generally though to be better, anyway) to the MPI head -- isn't working.
Does sound a bit like traditional petrol pooling.
But we know that the straightforward fitting of a P75 cam to an SPI (or MPI) head and inlet mani works just fine -- no loss of bottom end.
What are these bikes? Even on the old Desmo Ducatis we used to leave it 1500 to 2000 miles!
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:yeahthat:
The only loss of torque I felt is when the engine comes on cam which is about 250 to 500 rpm latter with the P75 cam. And for the record my SPI 1.2 8v with P75 cam feels just like a friends who did a P75 conversion complete with intake manifold just with less power and torque due to his better exhaust system.
The only loss of torque I felt is when the engine comes on cam which is about 250 to 500 rpm latter with the P75 cam. And for the record my SPI 1.2 8v with P75 cam feels just like a friends who did a P75 conversion complete with intake manifold just with less power and torque due to his better exhaust system.
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theres no way the fuel is pooling as the bottom of the ports are the same. its the top of the port that needs shaping to match the ports on the 75 head!
the lack of bottom end could very well be something to do with why my mckcrich chip throwing up the injector light! seems to run perfect with stock chip! :bang:
I definatly made it sound like theres a huge lack of bottom end. I did do a whole engine swap so I expect there to be big changes in power.
The bikes are a suzuki dr350 (supermoto, high compression piston (360cc) hot(ish) cam, HUGE flat slide pumper carb) I use this both on track and rarely street.
A CCM 350 rotax (same engine used in the armstrong MT 350/500 owned a couple of these) this was built for someone by CCM as a flat track bike. it was found to be to heavy so was used for hill climbs.
This bike has everything under the sun done to it.
and runs on methanol.
I do my DR valves at least once every 1k. the exhaust valves dont stay within spec for very long at all (the hardend face on the rocker arm wears out very quick)
*the pic of me and my dad on the track are taken from another track from the one with the van which was out last meeting*
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Ok just so i have got this straight in my own mind i can take a standard 1108 spi engine and so long as the shims and the tolerances for the top end are ok then a standard punto 75 cam shaft can be fitted and not cause any detramental effect to the day to day running of the engine. When i do get arround to doing this i will probaly port and polish the cylinder head for a better flow and go for a 4-2-1 exhaust manifold currentley it has an old conical shap piper cross induction filter and an Eco-teck cb26p valve fitted.
Yes.
But when you get around doing the porting and flowing (no pollishing of inlet ports and no exhaust port matching) you might as well get the MPI head and manifold and splice in the 4 injectors, which give you quite a bit more scope.
All you need to do then is to change fuel pump and preferably map it and you should have quite a quick car.
I do like the idea of putting a whole new head on and changeing to mpi but i am put of by the changes to the electrical side of things. Such as have to splice the loom's or get a re-map done as they can open up into a world of problems if it does not work properly. That and if i was going to the trouble of going to mpi and re-map i would be as well getting a second hand 1242 mpi engine and complete wireing loom and ecu and do an engine swap.
