For a laugh a I drilled them out and finished the edge off with a grommet. Yes, I know they won't do much in the way of cooling, but I think it looks rather good (better than a wasted recess anyway).
Sunday 26 October 2014
More on the venting
I mentioned in my last blog update about my musings regarding engine cooling via some movement of fresh air. Since then, I've cut the 5 holes just above the throttle bodies and added some mesh. With the engine run up to temperature, you can really feel the warm air rising from this area, so it can only be a good thing with regards to inlet temperature.
I was also pondering the very rear of the car and thinking about some holes just above the exhaust silencer. While doing one of my 35 min staring sessions with a cuppa, I noticed some recesses in the back of the rear clam. I say noticed, I mean remembered....these were originally meant for rear reflectors, but as I changed my light arrangement from what Sylva intended (reflectors were built in to rear light cluster), the recesses were redundant.
For a laugh a I drilled them out and finished the edge off with a grommet. Yes, I know they won't do much in the way of cooling, but I think it looks rather good (better than a wasted recess anyway).
And finally, I have just noticed a nice little area just in front of the rear wheel arch, that would fit a small(ish) NACA duct just perfectly. With one of these installed each side and some nice 50mm ducting pointing up towards the throttle bodies, I think I could really make use of the top vent holes.
For a laugh a I drilled them out and finished the edge off with a grommet. Yes, I know they won't do much in the way of cooling, but I think it looks rather good (better than a wasted recess anyway).
Saturday 25 October 2014
Ride height revisisted
Having now done a few miles to and from IVA centre, it was clear that the car seemed way to stiff at the front end. The springs were 200lb, and having now seen the axle weights, my guess is 200lbs is too much for 200kgs. Something needed to be done!.
In addition, I used an extension bracket to add an inch of ride height to the car to allow the front lights to pass the 500mm height requirement for IVA. This actually proved useful in that gave me effectively a 13" shock which suits the car better with the 13" wheels.
The bracket used was a) heavy, and b). borrowed, so it needed to come off. The solution was potentially to sell the 12" shocks and buy some 13", but a quick call to Gaz and a new set of shock tops were on their way to me with almost an inch increase in length...perfect and cheap solution.
That solved the ride height, but to also soften the front end a little, softer springs were needed. I put these on while replacing the shock tops. I've only gone down to 175lbs as I still want the car to be more track focused than road compliant, so we will see how the 175's perform.
This pic shows the different length of the tops, and the different colour of a 175lb spring!.
Another hot subject is the engine bay cooling :-)
not much in the way of free air flow with these rear engined cars. Look at any production car that has an engine stuffed behind the seats, and you will notice fairly sizable vents in the side to channel air in to either the engine bay or to a radiator / oil cooler. The J15 as standard offers very little in the way of air flow. Yes there are two small vents just behind the drivers and passenger ear, but that's about it. This means the engine bay (which of course includes the entire exhaust system) stays pretty.....bloody....warm. not so good on track days, and as the induction is firmly located behind the rear bulkhead, not so good for power as the warm air is far less dense than nice crisp cool air from outside the car.
So, what to do....Well, I've started by introducing some 'escape holes' into the rear clam. The first to be drilled are just above the air filter. The next step is to try and get some more air forced in. My plan is to place two NACA ducts and some tubes pointing at the air filter from below. That's the plan, and while I'm waiting for the DVLA to make a dream come true (and send me my plates), now seems like a good time to do these sort of jobs.
In addition, I used an extension bracket to add an inch of ride height to the car to allow the front lights to pass the 500mm height requirement for IVA. This actually proved useful in that gave me effectively a 13" shock which suits the car better with the 13" wheels.
The bracket used was a) heavy, and b). borrowed, so it needed to come off. The solution was potentially to sell the 12" shocks and buy some 13", but a quick call to Gaz and a new set of shock tops were on their way to me with almost an inch increase in length...perfect and cheap solution.
That solved the ride height, but to also soften the front end a little, softer springs were needed. I put these on while replacing the shock tops. I've only gone down to 175lbs as I still want the car to be more track focused than road compliant, so we will see how the 175's perform.
This pic shows the different length of the tops, and the different colour of a 175lb spring!.
not much in the way of free air flow with these rear engined cars. Look at any production car that has an engine stuffed behind the seats, and you will notice fairly sizable vents in the side to channel air in to either the engine bay or to a radiator / oil cooler. The J15 as standard offers very little in the way of air flow. Yes there are two small vents just behind the drivers and passenger ear, but that's about it. This means the engine bay (which of course includes the entire exhaust system) stays pretty.....bloody....warm. not so good on track days, and as the induction is firmly located behind the rear bulkhead, not so good for power as the warm air is far less dense than nice crisp cool air from outside the car.
So, what to do....Well, I've started by introducing some 'escape holes' into the rear clam. The first to be drilled are just above the air filter. The next step is to try and get some more air forced in. My plan is to place two NACA ducts and some tubes pointing at the air filter from below. That's the plan, and while I'm waiting for the DVLA to make a dream come true (and send me my plates), now seems like a good time to do these sort of jobs.
Tuesday 21 October 2014
IVAAAAAAAAAAAAAAAhhhhhhhhhhhhhh.....tis done m lud :-)
Goodness me, it's been a while since last post, but that's not to say nothing has been going on. To be honest, I can't remember all the various bits that I've done but it matters not......IVA is done and dusted.
It went through on the second attempt after a couple of surprising fails first time around. 1st was the wing mirrors. Basically they were not high enough to view the bottom dot on the IVA testers wall. Interestingly, other J15 builders had used the same mirrors and put them in the same position, but mine were 'way out'. Second on the list was the noise level. The pass mark was 100dBs and the J15 came out at 102dB. The issue here was not the exhaust noise but the fact that the engine was / is right next to the exhaust, so the meter picks up both exhaust and engine noise. Not good!.
Anyway enough of all that fail rubbish....retest took the best part of 20 mins, and with my new 4 inch mirror extensions, and 30 quids worth of sound deadening in the engine bay, she flew through. Job done. Since IVA, and by that I mean approx 36.324 mins after IVA, the look of the car has changed a little. The 'not so nice' mirrors have vanished (I think someone stole them), and as luck would have it, I had spare SPA central mirror, and some e-tech wing mirrors.
Also the steering wheel now looks 'different'...it's reduced down to 270mm, and a nice 90mm extension, and now sits perfectly where I want it with the added advantage that my knees don't hit it when driving. The experience is much more 'race car' like when sat in the drivers seat.
Other new additions are the two light covers, which I've been gagging to fit, but have resisted until through the IVA. These make a huge difference to the look of the car. The fitment of these is not great, as the mould of the front clam is not really designed to take them (i.e. there is no lip for them to sit in). But, nonetheless they certainly improve the look of the car in my opinion. I made the fixtures using some stainless washers bent over, then tapped a thread through them to take an M4 hex bolt.
And finally....back to the wheels. I've ditched the image split rims as I was never really quite happy with the size and fitment (mainly the offset). The previous rims had an offset which pushed them out of the arches, but not quite to the edge of the arch extensions. They were also 7 inch and although ok for a 185 tyre, was not optimum. So, I've reverted back to compomotive CXR's 6.5inch all round with an offset of ET01.
Well, that will do for now......I'm going to stop writing this and get on with what I should be doing, which is completing the DVLA forms!. Here hoping I get to drive it before the end of November.............2014 of course.
It went through on the second attempt after a couple of surprising fails first time around. 1st was the wing mirrors. Basically they were not high enough to view the bottom dot on the IVA testers wall. Interestingly, other J15 builders had used the same mirrors and put them in the same position, but mine were 'way out'. Second on the list was the noise level. The pass mark was 100dBs and the J15 came out at 102dB. The issue here was not the exhaust noise but the fact that the engine was / is right next to the exhaust, so the meter picks up both exhaust and engine noise. Not good!.
Anyway enough of all that fail rubbish....retest took the best part of 20 mins, and with my new 4 inch mirror extensions, and 30 quids worth of sound deadening in the engine bay, she flew through. Job done. Since IVA, and by that I mean approx 36.324 mins after IVA, the look of the car has changed a little. The 'not so nice' mirrors have vanished (I think someone stole them), and as luck would have it, I had spare SPA central mirror, and some e-tech wing mirrors.
And finally....back to the wheels. I've ditched the image split rims as I was never really quite happy with the size and fitment (mainly the offset). The previous rims had an offset which pushed them out of the arches, but not quite to the edge of the arch extensions. They were also 7 inch and although ok for a 185 tyre, was not optimum. So, I've reverted back to compomotive CXR's 6.5inch all round with an offset of ET01.
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