who builds the best engine for motorsport in the uk

On my race engine build post, there was a discussion about this, about 6 months ago. Net result is that I was advised the ramp profile was different on a hydraulic, so I bought a set of 300 degree kents mechs, to replace the 300 piper hydraulics. Engine is now running. If the profile was the same, then the cam manufs would only stock one profile, wouldnt they?

 

Hydraulics effectively run 0 clearance when all pumped up, solids will run at 10/12 thou/0.25mm, this affects the ramp rate. Also, hydraulics don't like too much acceleration rate or they can pump down. Hence two seemingly similiar/idetical profiles will be different.

You can run hydro profiles on solids but it won't necessarily give the opening/closing characteristics suggested on the cam sheet.

 

Is that a definitive statement? If so, I have a nice pair of secondhand piper hydraulic/mechanical 300 degree piper cams for sale 250 plus postage. (their replacements cost me nearly double that!)

 

In theory hydraulics should run zero clearance , as there design is such that as soon as you build up oil pressure they will expand until they touch the cam , as engines get hotter and oils get thinner , there must be some compression in them , I can't see them running zero clearance perfectly all the time.

The ramp angle on cams designed to use with hydraulic lifter will not be as severe as mechanical cams , if they were they would compress the hydraulic lifters and stop them working properly , so in effect they are making the cams milder to get around a problem.

Fitting solid lifters is the better way as once they are in , they are in , no matter how hard you drive , what cam profiles you run , they will never change and never compress , in a highly tuned engine they are a must. So yes in my eye's you can run solid lifters on any cam , ok in theory if you set them at a certain clearance they you should have slightly less lift , which then goes back to my thoughts on does a hydraulic lifter retain its zero clearance all the time ?

I remember the days of adjustable lifters on most road cars lol , my grandad or father tinkering around with there cars on weekends setting tappet clearances on noisy engines , hydraulic lifters were a godsend when these came out as it stopped you having to do this , great on a road car for less maintenance , not in a high output tuned engine !

 

I dont doubt what you are saying, but can others coroborate (spell) this please

 

If you're going for ultimate power (and as a result, sustained high RPM) then I don't doubt that solid lifters are the way forward, However:

from 20+ years of watching, and some minor participation in, club motorsport, I'm of the opinion that a lot of people don't have the skills to drive their car, and would be quicker with a less powerful, more driveable car (and I'm not suggesting that this applies to you Jon, as I've never seen you drive, and I know you've been at it for a long time.).

...because:
- They've spent all the money building a revvy, peaky engine, and can't keep it on cam because the transmission doesn't match the engine.
- or because the type of event they're doing (e.g. tight and twisty single venue rallies with unpredictable surface changes) means it's almost possible to keep a 'full race' engine on cam.
- Poor setup of the engine limiting the driveability.
- Talent deficiency (after all, they're amateur competitors, and levels of experience and ability vary a lot)

So if you're working on a limited budget, I think there's a reasonable case for building a milder spec of engine, spending a bit more on gearbox/tyres/suspension/setup, and ending up with a better overall package - easier to drive, more reliable, less expensive to build/run/maintain.

So a well set up 2.0 16v on 276-ish cams and well set up management should give you around 200 bhp, but have a wide torque band and be easy to get the best out of it. A lot of club drivers would be quicker in this than a 250 bhp 8500 rpm screamer, with no power below 4-5k.

 

If you keep the revs down there is nothing wrong with hydraulic profiles with hydraulic cams. As Mike_H says there are other factors that will contribute in the grand scheme of things.

With regards to mech vs. hyd profiles, if you look at many cam books (kents for example) they tell you at what clearance the duration is quoted at. In Europe it's usually the same as the installation clearance (as I said ~10 thou/0.25 mm or 0 for hyd) in the US you often get durations quoted at 0 for solids and then sometimes the same book will quote @ 10 thou or some other clearance. This is why durations in the US can appear shorter, because the cam timing is set at zero with the rockers/buckets closed right up, and then loosened for actual running.

My point being that the cam and lifter interaction and therefore the valve lift profile is greatly affected by this clearance, which is designed into the cams. Hence two profiles both called "road racer 123" & "road racer 123(hyd)" can have identical valve lift curves which is what the cam designer had in mind and then the lobe design has geometrical differences depending on valvetrain.

 

Mike: Another viewpoint, which is always good for a chew on. If I could have a bit chew, I hear what you are saying and this massively is true on sports bikes, another hobby of mine.
I remember buying one of the first gsxr11's and that thing would pull your arms off, but it bhad to be on the cam, >4500 or about 90 in top. I never had the gonads to get it flat in top. ie it was too much for me to handle.
Back to cams. I have done quite a bit of racing on a loose surface, and this is a very specific application.
Basically, the front wheels are spinning 80+% of the time, making it great to keep the engine revs in a power band. If it drops below 4K, you have chosen a wrong gear or wrong line . Hence my need to build a solid lifter 8K safe engine

 

Had to break for T mid sentence.
More of the same. My build thread for the 2L16V I have just got running asked the same cam duration / area under the torque curve question. I was hoping for some 'mike type' input prior to buying the parts I did. I didnt get the value of the broad experience you guys have. So went for 300 mechs.
Tarmac rallying: Agree, lugging 14 stone of passenger around, sumpguards, etc etc means full race spec is not the best solution for clubmen like me.
Probably the best of my engines in the mk1, so far, was a 9A with a longman head, luminition TB's/ECU on 276 schricks. Fat 150+ ft/lb over a good spread.
At the other end of the spectrum, when I raced formula C rallycross (1600's) (around 92-94) I had a GS6 cammed 8v that was so cammy I eventually sold the gsxr11 to spend all the cash on an ultra CR VWMS 16V gearkit and plate LSD. Good times..

 

Just an update , spoke to the guy fixing the head for me , he has welded the damage , just needs to machine it back , he has re-cut all the valve seats , he said some of them were leaking quite bad , some were oval , so not good at all , no wonder the compression ratio's were all over the place.

Should have the head back finished within a week , will get everything down to Mr Hillclimber to see if he can see if he can improve on the porting , then build the engine and map it for me.

I have got it running again today by fitting a standard engine , I have ordered 120mm horns for the throttle bodies today to up the torque as it only has 45mm ones on , will get it mapped when they are on ready for the wyedean rally on the 11th Feb so at least I can do the rally.

The more I'm reading about the FSI heads , the more its getting me thinking lol hmm , what to do !

 

what make/supplier for the 120mm horns? DCOE pattern fixings? or to suit the TB's. I was going to try making some plastic ones on the lathe, so I can try different lengths on the rollers

 

Ordered them from jenvey , hopefully get them tomorrow , got them to fit my direct to head throttle bodies

 

Got the head back today , he's done a very good job with it , has also recut the exhaust seats as they weren't sealing properly









Jenvey didn't get the horns to me , so hopefully get them tomorrow so at least the cars usable , hopefully can get the rally engine rebuilt in time to d another rally in March

 

Nice looking head

 

Glad to see the head was repaired...