old captain slow Posted April 16, 2006 Share Posted April 16, 2006 Just a sanity check please. I've fitted the VVC plenum to my 1600K and of course it conflicts with the bonnet cover as it's too high. I've taken about 1mm off the top corner of the plenum down it's entire length, and dropped the engine on the nearside by about 4mm by trimming the nearside engine mounting by that amount. I still need another 2mm or so to get clearance to the underside of the bonnet as the plenum still contacts the bonnet but only just. Do you think I'm ok trimming say another 3 or 4 mm off the engine mount or should I trim the other side? Any clues as to how much material you can take off the top of the plenum without punching a hole in it. Seems to run fine on the SS map but presumably I need to bite the bullet and get it mapped on an Emerald to make the most of the better breathing (52mm TB). C7 CDW Edited by - david w on 17 Apr 2006 19:16:52 Link to comment Share on other sites More sharing options...
Myles Posted April 16, 2006 Share Posted April 16, 2006 David, You should really look into splitting the top and bottom halves of the plenum and removing material there as your next port of call. Depending on your chassis, the main diagonals might (or might not) have 'dimples' in them to give you a bit of extra space underneath the plenum feeds to #3&4 cylinders. My race chassis doesn't have the dimples and the clearance between the diagonal and the underside of the plenum was one of the major factors that caused me to abandon the idea and fit Jenveys instead. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
old captain slow Posted April 16, 2006 Author Share Posted April 16, 2006 Just had a quick look. I hadn't checked for this. My chassis doesn't have the dimples either, but fortunately there is still about 2 - 4mm clear between No 4 intake and the cross brace. The max torque from the engine is only around 120lb ft. I wonder if I'm going to get problems with engine mount compression under steady state or dymnamic torque more than this clearance? I don't want to get into machining the plenum if I can avoid it. I think I'll put a bit of blue tac between the plenum and the cross brace and see if it compresses under "beans" and the "shock" after gear change. I've taken the gasket out and sealed it with gasket goo in a thin smear instead. That saved about 0.5 mm! The bonnet actually fits fine. It's just say touching. I'll see if it rattles. I guess that's the only other issue if it's touching or just say clear. C7 CDW Link to comment Share on other sites More sharing options...
Mick Day Posted April 17, 2006 Share Posted April 17, 2006 Sorry to be a kill-joy but if it's just touching it'll probably wear through the bonnet over time. I've seen a rad holed this way where it was just touching the nose-cone. Link to comment Share on other sites More sharing options...
caterhamnut Posted April 17, 2006 Share Posted April 17, 2006 I will be having these issues in a few weeks (hopefully) as we move to a VVC plenum. I have solved it by machining the top off the plenum, lowering it by 5mm or so, and then welding a flat plate on top. I think the Caterham fix of a new, lowered engine mount only on one side is not a good engineering solution - it twists everything else IMO. The other thing that we have done, as Myles also suggests, is machine some metal from between the two parts of the pelnum, to lower it, and also I have angled the face of the plenum where it bolts to the engine, to bring it down slightly. One thing to be aware of which I only just found out is that you need a VVC clutch cable the standard one has a length of adjustment thread and associated nuts, that the plenum will hit. About £30 from Caterham.... Second what Mick says about bonnet wear - our car has a 'slot' cut in the bonnet wear the previous onwer had not tied the accelerator cable down, and this has chaffed its way through the metal as it loops over to the TB. www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Edited by - angus&tessa on 17 Apr 2006 11:05:37 Link to comment Share on other sites More sharing options...
Myles Posted April 17, 2006 Share Posted April 17, 2006 Angus - regarding the clutch cable - I remember asking CC parts about this (and the technical helpline) and they told me that there wasn't a VVC-specific part. They told me that the cable will interfere with the plenum and that's that. I was a bit surprised about this as I thought people had discussed a VVC-specific cable. In the end, I never got to the bottom of this as I went for Jenveys. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
rj Posted April 17, 2006 Share Posted April 17, 2006 I think the VVC always has hydraulic clutch /regin Growing old is mandatory - Growing up is optional Link to comment Share on other sites More sharing options...
caterhamnut Posted April 17, 2006 Share Posted April 17, 2006 Marvelous isn't it! You would think they would know (maybe it is a newly introduced part?) here - 3rd item down. www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
rj Posted April 17, 2006 Share Posted April 17, 2006 *eek* *eek* ❗ Growing old is mandatory - Growing up is optional Link to comment Share on other sites More sharing options...
old captain slow Posted April 17, 2006 Author Share Posted April 17, 2006 Ok guys and gals here's an update. - Shaved about 4 mm off the rh engine mount (hope I haven't b*****ed it). - Left out the gasket between the top and bottom part of the plenum and sealed the gap with a thin smear of gasket goo. - Filed about 1+ mm off the top of the plenum chamber. - packed blue tac in the gap between the chassis cross brace and No 4 cylinder inlet pipe to see if the engine moved significantly under torque reaction. - Put a strip of gaffer tape along the top of the plennum to check for scuffing and went for a short run. Clear scuff marks on the tape so clearly going to wear through eventually. So "eased" the bonnet at the louvres where they were touching ie stretched the ali a small amount by rubbing a suitable piece of soft wood on the back of the bonnet while it was resting on several layers of heavy cloth. Result about 1mm clear achieved. Blue tac compressed by about 1mm by the engine torque reaction after several max torque applications and solid gear changes, so the gap between the plenum and the cross brace at 3mm plenty enough. Went out for a proper test run and gave it full beans. There is a marked increase in performance, particularly more torque apparent particularly at the higher revs. Won't be able to judge properly until 22 May when I'm putting it on track at Combe. I don't think there are any issues with the clutch. The cable does press against the plenum but the misalignment is very small. Time will tell but the clutch cable is pretty easy to change anyway. I'd like to fit an Emerald ultimately and get it mapped properly. On the basis of results achieved with Williams 1600K running with the 1400SS ali plenum where it achieved 148 bhp at 7200 and 119 lb ft at 5100 I think 150 bhp should be achievable. C7 CDW Link to comment Share on other sites More sharing options...
caterhamnut Posted April 17, 2006 Share Posted April 17, 2006 Thanks for the update - good to hear that the clutch cable is not such an issue - over £30 for the VVC special from Caterham 😳 www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
PAUL MARRIOTT Posted April 17, 2006 Share Posted April 17, 2006 When I ran mine on a VVC plenun I used the standard clutch cable for a year without a problem. Paul M Link to comment Share on other sites More sharing options...
caterhamnut Posted April 17, 2006 Share Posted April 17, 2006 *thumbup* www.mycaterham.com here 91,000 miles -1st 1.6k Supersport, '95 Motor Show car Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now