GW 200 CUP (clubsport->racecar->v2)

I dont think you can get to 220 with just usual breathing mods and Piper cams,Liam also has high comp pistons so I would have thought without you could get to around 215.
Yep exactly.
If you've got the money you can get a built engine with ITB's to around 240-250Bhp but for what that costs it's cheaper to go forced induction or engine swap for bigger numbers.
 
Turning up to the unit over the past few weeks with fun stuff to do has been a joy, a year of turning up with the prospect of pulling out an engine I just put in or deadlifting a box has been draining.

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First job was to dump the break in oil, I have put some fresh running in oil for at least the next 100 miles to give the rings some more time to bed in but it’s probably overkill. The oil was also nice and clean but next time I will drop the sump to get rid of all of the lube / arp grease used on the build.

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From the track day last year it was the pedals that really annoyed me, got some time to investigate and found that the throttle pedal had been bent so that it was closer to the brake. The problem is the angle it has been bent at means it’s closer when pressed which explains my lack of confidence on where my feet/pedals where.

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Using my old pedals I have been able to replace all of what was there and I am a lot happier, might want to make the throttle pedal larger but will try standard again for now.

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Door pull bolted on, another annoyance from using the car, the fibreglass bends slightly but it will do the job.

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Tegiwa transponder bracket bolted to NS wheel well, has a clear view of the track and one less thing to worry about.

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Finally finished the nozzle placements for the fire extinguisher, I rate the system in terms of safety but the Ali tubing is a pita, I have spent hours setting this up, it’s so time consuming. Just need to wire it up and it is finally complete.

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Amazon special grating added to the front bumper as some protection to the rad, I really want to get rid of some of the holes from the front but that can wait for now.

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Very much ready for a track day but waiting for the weather to improve for now…
 
I thought I had hit the bottom last year, apparently not.

Spent the last few weeks doing fun stuff on the car, fire extinguisher wiring, hazards/heater wiring, ABS sensor issues and various small but satisfying things as I waited for the weather to improve.

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Last minute day booked last week for Friday as the weather was finally looking good, feeling positive as the car felt good driving around the paddock and passed the noise test with no issues and temps/oil pressure all looking good (4-5 bar under load)

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However I noticed on the sighting laps that the car didn’t like being put under load when in a high gear, it felt like a light juddering as it got up to revs (2.5-3.5k) At the time I put this down to a flat spot due to the high comp / cams etc as it didn’t seem to occur at any other rev ranges but it was certainly in the back of my mind. Sorry for the watermarks but I feel the pictures help tell the story better..

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Took the first 40 or so laps slow as I built up the revs and made sure temps looked good as well as doing a nut and bolt check on the frontend as most of that had been off to fit the engine.

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I then started pushing the car, the chassis felt great, the frontend combined with the low weight and direzzas is just mega, optimal started to dip into the 54’s but I am no where near its limit. However the top end power was just not there, it was a weird feeling and it felt like the car got heavier / draggy as I went faster / into higher gears.

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I assumed this was either the spoiler or me, took the spoiler off and looked to compromise the entry to clearways to try and get a decent exit to try and remove as many variables as possible. No difference in top speed, engine felt strong but something was wrong, just couldn’t work it out especially as the dyno was pointing to this engine being very strong.

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Took lunch and started looking at the data, here is a comparison between the day and Oct 22 with the old car/engine but in the wet. You can see the massive difference in starting speed but higher finish speed by the start/finish line! As well as a near flat line of acceleration by the end (white line)

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I noticed that my gear changes are a lot earlier in the current car, I assumed this was because I was going faster but I am actually changing much earlier in terms of wheel speed even though I change at the same revs / engine speed (second screenshot). I then remembered how it behaved during the sighting lap and put two and together realising that it was very likely the clutch slipping when under high torque. This would explain the disparity between revs/speed, the juddering and near flat lining of speed when in 5th gear. The dyno obviously loads the drivetrain up slowly hiding the clutch issue until it was on the track.

Not sure if this is due to the higher engine power or the lightweight flywheel I put on has not bedded with the clutch. I am using my old clutch but the flywheel face from memory looked brand new, happy I had diagnosed the issue I decided to keep going but ignore the lack of power.

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First session after lunch, 3 laps in and just started to put the power down this happened.


Worst nightmare, I assumed at first it was either a coil/plug has been launched out of the engine or the clutch/plate had exploded. Pulled the plugs, #4 looked good, #3 looked good, #2 looked good and #1 looked like this:

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It's quite obviously dropped a valve, I can also see bits in cylinder 4 as well but I believe that is common due to the exhaust manifold design.

The irony of where it happened has not been lost on me with it being the following corner to my crash and right next to the pit entry meant I coasted almost all the way back to the garage. Why it has happened I don’t know, overrev? build error? component failure? unlucky? Probably all 4 as maybe I was pushing her probably a bit too hard on a fresh build, who knows. One thing to note is that the inside curb vibration seems to cause the final blow but I doubt that was the real reason.

So at least one piston is dead, head is going to be scrap, bores are going to be scrap, valves scrap, likely further damage depending where the valve ended up, you can see I disengaged the engine quickly before it died but it sounded horrific.

But fuck it I am going to buy a new engine and race this car, I have a potential candidate, stay tuned.
 
Pulled the engine, no surprises with the exhaust valves in cylinder 1 looking a little bit broken.

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I have found pieces of engine in the throttle body and I still need to pull the manifold to check the cat survived.

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Hard to tell with the head on but it looks like the valves in 4 might be bent as well so I think it’s safe to say everything needs to be replaced on the top end. Haven’t dropped the oil yet but the bottom end might have survived, ignoring the pistons. Although not sure how wise it would be to use the rods considering the force they have been subjected to trying to compress a valve head.

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My current concern was the clutch/ flywheel, the clutch itself and pressure plate looks ok. However does this flywheel look glazed? Am I mad to just give it a deglaze with some emery and send it?

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The run out looks within spec so I can only assume the process of bedding the piston rings in has resulted in this glazing. This is assuming this is the cause of the slipping as I am under the impression the plated diff wouldn’t do this. I tested the break away torque anyway and it comes in at about 90Nm which I believe is normal / I had no issues on corner entry / exit.

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I have sourced an engine, 99k miles with decent service history. Current plan is to give the bottom end a refresh, with new bearings, pump, gaskets etc and just send it. Assuming it gives 200BHP (ambitious) I could then ballast the car 30/40kg and be at the top of class B for Hot Hatch (175 BHP/T) rather than A. On this note does anyone have a spare ECU?

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There is the temptation to move the cams across and aim for class A still but I run the risk of the same thing happening again if I don’t upgrade the rest of the head. At this point I just want a summer of having a car and potentially work on building another engine for next year.
 
I agree with the above.

Fly looks fine to me too. I’d also have no problem using them rods again personally.
 
Don’t think so. Are you sure it was actually slipping?
I’d have expected more colouring and spots if it was actually getting warm.
 
Don’t think so. Are you sure it was actually slipping?
I’d have expected more colouring and spots if it was actually getting warm.

Nope, I am seeing what seems to be clutch slip at high gears / rpm but no apparent evidence, unless I am being stupid the only reasons I can think of:

- Slipping clutch
- Slipping diff, I don’t think a plated diff would result in this?
- ECU pulling the timing

I don’t think it’s the ECU due to the juddering at low speeds and no stored error codes. Higher load is certainly causing it as you can see the speed of the car almost stall when going up the hill on the start/finish straight.
 
Yeah I'm pretty stumped to be honest.
I'd have expected you would smell it if it was slipping that much.

Have you had the engine apart yet?
Perhaps you've knocked a valve and were losing compression before the failure happened.