Cost effective ways to reduce under bonnet temps

davekmoore · Postby **davekmoore** » Thu Sep 04, 2014 9:18 pm

davekmoore wrote:Yes, this was my final conversation with my (ex) tuner, even though he now works for free. The killer was that for extra under bonnet cooling he also suggested bonnet lifts, as used on all his V8 projects!

In case I failed to make myself clear, this means I will no longer be using this tuner. The final straw was his suggestion to use hood lifts. I'm only a salesman on a steep learning curve, not a technician, but I did already know bonnet/hood lifts are wrong on an MX5/Miata. His talk about his V8s having 30 degree under bonnet temps, partly because of hood lifts, convinced me he's possibly good with V8s but not with MX5s.

Lesson learned: Do not stay too loyal too long to that which seems wrong.

sailaholic · Postby **sailaholic** » Thu Sep 04, 2014 9:32 pm

Dave also might depend on if he's talking at speed or in traffic. I would think a bonnet lift WOULD work in traffic as it give an escape for the hot air as there is no high pressure zone at the windscreen.

Either way I think you made the right decision.

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gslender · Postby **gslender** » Thu Sep 04, 2014 10:01 pm

I see that you can download the ECU Manager software from Haltech. Might be worth having a look, and possibly with a bit of google work and forum discussion on the Haltech site you might be able to figure it out for yourself.

I'd at least get a log from the ECU and figure what's going on when it's hot and idle is poor. Do you have an wideband O2 sensor installed?

davekmoore · Postby **davekmoore** » Thu Sep 04, 2014 11:10 pm

Pics as promised. Couldn't find a way to show full sized ones so hopefully these will do for anyone prepared to give the time to offer ideas. It seems clicking on them enlarges them. It's taken me all evening to post them and even now they enlarge rotated! Sorry.

Underbonnet cold side small.jpg

Under bonnet hot side small.jpg

Under bonnet whole motor small.jpg

Postby **Okibi** » Thu Sep 04, 2014 11:57 pm

A heatshield on the pod would help, is the top radiator hose flattened out?

gslender · Postby **gslender** » Fri Sep 05, 2014 7:41 am

If you are getting under bonnet temps from the AIT where it is mounted in the pics then it wouldn't be the true air temps. That AIT would be heat soaked from the radiator and not the true air temps. Any good tuner would know that. Get another tuner.

Stop worrying about under bonnet temps. Nothing to see here. Move on.

sailaholic · Postby **sailaholic** » Fri Sep 05, 2014 8:33 am

Except maybe the top radiator hose could be a worry.

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sailaholic · Postby **sailaholic** » Fri Sep 05, 2014 8:45 am

Actually G, the SE ran two IATs from the factory. The usually one in the MAF but there was a second near the throttle body that the ecu actually used for the real work I believe. So it probably depends which one the tuner used.

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gslender · Postby **gslender** » Fri Sep 05, 2014 9:42 am

sailaholic wrote:Except maybe the top radiator hose could be a worry.

Meh, maybe not... an engine cooling down where the top hose is fairly new / soft will do that as it cools and sucks coolant back out of the overflow... but if that's its steady state shape (hot or cold) then yep I'd be replacing it.

G

bruce · Postby **bruce** » Fri Sep 05, 2014 9:43 am

That is an unattractive bonnet vent. I don't know if a good looking one exists.

davekmoore · Postby **davekmoore** » Fri Sep 05, 2014 9:50 am

gslender wrote:
sailaholic wrote:Except maybe the top radiator hose could be a worry.

Meh, maybe not... an engine cooling down where the top hose is fairly new / soft will do that as it cools and sucks coolant back out of the overflow... but if that's its steady state shape (hot or cold) then yep I'd be replacing it.

G

It's new. It goes back to normal shape when running.

gslender · Postby **gslender** » Fri Sep 05, 2014 10:52 am

sailaholic wrote:Actually G, the SE ran two IATs from the factory. The usually one in the MAF but there was a second near the throttle body that the ecu actually used for the real work I believe. So it probably depends which one the tuner used.

good point. I guess if the tuner is saying "errr, bad idling problems... err, probably air temps too high when sitting still, fix it with better cooling"... so we are probably guessing wildly and no photos will help... the solution isn't cooling air temps as that's normal and common even in production engines. Think about how cool the NA/NB air temp would be with it sucking air from the hot side near the stock headers... not cool at all !!

The problem is a bad tune where the ECU or tuner isn't adjusting the idle for all conditions - it is probably leaning out too much when really hot. You just need to richen the idle cells or tables and yep, when just warm it will idle fairly rich, but so what... its idling and you never get much of a good fuel economy anyway.

G

gslender · Postby **gslender** » Fri Sep 05, 2014 10:54 am

...also, is the idle problems when running on e85 or regardless when running normal PULP etc... ???

Magpie · Postby **Magpie** » Fri Sep 05, 2014 10:57 am

Bruce I have an attractive GV bonnet that has a vent just behind the radiator. However I run the risk of a defect in QLD as it is made of fibreglass.

Here is my GV Bonnet

Not mine but another GV NA

GV NB Bonnet

sailaholic · Postby **sailaholic** » Fri Sep 05, 2014 11:37 am

Surely it should have a coolant enrichment table (allowing positive and negative values) separate from the normal fuel map to counter iat temp increase? Or is this normally reserved for tuning fuel corrections on load.

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