DIY Honda Conversion

Rich H · Post by **Rich H** » Tue Aug 14, 2007 11:46 am

A NACA duct might be the way forward, but you'll need a metal one a placcy one might melt!

Dom: Straight 6 might need some bodywork to fit...

Any chance you could measure it for me? I have a 924 with a van engine that needs a boost....

YvoTuk · Post by **YvoTuk** » Tue Aug 14, 2007 12:15 pm

I think I will go with the Nacaduct solution. Just had a chat with a Honda dealer (who actually knows the setup in my car). He told me he didn't understand why the heatshield was removed in the first place.

The Naca duct can be plastic / or GF with a round exit hole..

Rich H · Post by **Rich H** » Tue Aug 14, 2007 12:35 pm

I was concerned that if the temp is as high as it seems a fadricated ali one might be a better choice,

Put the heatshield back on and get the air flowing in there (I bet the airflow if poor at best) and they might last longer....

garyk220 · Post by **garyk220** » Tue Aug 14, 2007 1:33 pm

NACA duct and pipework to driect cool air to the heat source sounds like a good idea.

The VXT turbo has an additional NACA duct in the undertray (3 ducts rather than 2 in the 2.2) to draw cool air through the engine bay and via the turbo ducting/chimney out through the engine cover vents. Lotus spent a long time developing this solution to manage the engine bay temps and prevent the radiated heat from the turbo melting the chassis glue.

woody · Post by **woody** » Tue Aug 14, 2007 1:45 pm

As I understand it, is the clearence required by the elise manifold not significantly less than that of the standard manifold? Would it not be possible to fabricate perhaps a ceramic coated sheild that would fit while offering far greater heat protection?

DDtB · Post by **DDtB** » Tue Aug 14, 2007 1:46 pm

woody wrote:Would it not be possible to fabricate perhaps a ceramic coated sheild that would fit while offering far greater heat protection?

Well volunteered that man!

woody · Post by **woody** » Tue Aug 14, 2007 1:50 pm

DDtB wrote:
woody wrote:Would it not be possible to fabricate perhaps a ceramic coated sheild that would fit while offering far greater heat protection?
Well volunteered that man!

Our ceramics get done in godknowswhereland now

YvoTuk · Post by **YvoTuk** » Tue Aug 14, 2007 2:13 pm

I've seen at least one pic of an original Honda heatshield installed together with an Elise manifold, it looks like quite a tightly fitted heatshield over the intermediate shaft.

I think that shield alone will already help as it will stop radiation heat. It will ofcourse be heated by the manifold, but that's not bad as long as it's not getting as hot as the manifold itself. If there's enough space, I'll also try to cover it with a layer of Cirrus which will definately stop the heat from coming in..

The more I see, the more I think the problems are not related with angles, but with heat transfer.

mac · Post by **mac** » Tue Aug 14, 2007 2:46 pm

That's pretty much what Craig said to me at TT's.

It's the heat that kills the CV joints either by the means described earlier in the thread or with excess expansion of the CV gaiter due to increase pressure causing it to pop off and the grease being thrown out.

Mac

YvoTuk · Post by **YvoTuk** » Tue Aug 14, 2007 2:54 pm

It's the air inside the boot that gets expanded. I've tried to 'vent' them using long injection needles, but they kept throwing out small amounts of grease, so I stopped that.

I think the idea to vent the boots is quite good, the only problem is you'd have to find a way to stop if from bleeding grease.

I've still got some idea's about that

Rich H · Post by **Rich H** » Tue Aug 14, 2007 3:26 pm

If you vent them at the narrow end the centrifical force will keep the grease thrown out to the edges but the air will escape from the centre. Possibly. Maybe a small pipe cable tied along the driveshaft into the narrow neck of the boot, IYSWIM.

Or inject the boots with grease while venting the air so there is no air to expand?

YvoTuk · Post by **YvoTuk** » Tue Aug 14, 2007 3:51 pm

That's exactly what I've done with the injection needles, but it kept throwing out grease

woody · Post by **woody** » Tue Aug 14, 2007 3:57 pm

YvoTuk wrote:That's exactly what I've done with the injection needles, but it kept throwing out grease

Make a sleve with a reverse therad on it to fit over the shaft. The thin end of the boot then goes over the thread, air escapes, but grease will tend not too. Slight adaption of gas turbine sump theory.

tut · Post by **tut** » Mon Aug 20, 2007 8:06 am

As Yvo says, heat transfer from the manifold to the intermediate drive shaft/tripod CV joint is the killer. The Honda heat shield and spare S/C belt that were sent to me arrived after I left for FF6, thanks to the f***ing postal strike.

However I wrapped the shaft with metal tape, and after thousands of miles and three track days, I could not believe that I was actually driving the car home on Saturday.

I feel much more confident in the cars reliability now, and although I thought that I would take it easy on track to try and get through to the second week, that never happens of course, and I was out there most of the time.

Dijon, and Charade in particular, were very grippy and hard on the cars, and I was up to 152 tuts at the end of the formers long straight, so very heavy braking as well into a tight right hander.

I hope now that with the tape and the heat shield fitted, I maybe able to get a decent life out of the tripod joint.

tut

r10crw · Post by **r10crw** » Mon Aug 20, 2007 8:31 am

Realistically how much reliabilty do you want from a car that has P/W matching a seventies F1 car. So far the only serious issue Ive had with the install has been the cv joints. Initially they would last until the car was pushed, everytime I went out with tut to test the cars (and I mean everytime) she would throw a boot. Ive now cured this and no matter how hard I push I cant throw the outer boots. Incidentally we were at high speeds on a bumpy road each time, it seemed the travel in the suspension caused it, perhaps engine position? Anyway the inner has yet to fail, maybe because the exhaust is ceramic wrapped, the shaft tape wrapped, and also using needles in the boots. Another thing is the boot manufacturer Im now using VW boots which seem to be lasting pretty well.
Either way the joints are now lasting thousands of miles and Im now able to change a CV joint in less than two hours which means I dont mind so much when/if they fail!!