Jump to content
The mkiv Supra Owners Club

GT74 High Compression Six Speed


Terminator

Recommended Posts

  • Replies 375
  • Created
  • Last Reply

Top Posters In This Topic

I was very pleasantly surprised to find that during the seven mile journey, which included 30 mph zones with slow corners and junctions and a couple miles of WOT reaching 8300rpm, the intake temperature stayed at 23 degrees. .

 

without raining on your parade Termy this sounds impossible as the compression of air produces lots of heat, you would be looking at 100% intercooler effeciency, i had a problem doing this a while back introducing a thermocouple into the intake tract, the T/C wire shorted on the intercooler pipe when tightened the jubilee on the pipe, this caused the thermocouple to read the temp of the pipe not the air

Link to comment
Share on other sites

I don't think 100% efficient inter-coolers exist;). I will try to stick a a thermo couple in the outlet tonight and get some readings. We must have got a pretty good airflow through the cooler as the temperatures drops off rapidly as the car moves off and picks up speed. I have another camera now so will try to get some footage.

Link to comment
Share on other sites

without raining on your parade Termy this sounds impossible as the compression of air produces lots of heat, you would be looking at 100% intercooler effeciency, i had a problem doing this a while back introducing a thermocouple into the intake tract, the T/C wire shorted on the intercooler pipe when tightened the jubilee on the pipe, this caused the thermocouple to read the temp of the pipe not the air

 

Ah I see where you are coming from. Perhaps my post was not clear. I was referring to the temperatures at the air feed to the turbo, ie air from the filter. After years of hype about the need for air boxes etc, I was expecting to get much higher temperatures as I assumed under bonnet air would swirl round and get into to filter especially at slow speeds or when stationary. With low filter temperatures there must be less engine bay air particulates for the filter to cope with.

 

I will get a probe in the turbo exit and see what the inter cooler is having to cool.

Edited by Terminator (see edit history)
Link to comment
Share on other sites

The N/S engine bay is a bit crowed and has taken quite an effort to fit it all in. The position of familiar items is unorthodox, but it all fits. The feed to the TB is 102mm, which drop's to 90mm for the Q45 TB. The Tial bov fits well up behind the head light. The fusebox had to be altered to get it to fit. The power steering reservoir was moved slightly back from the stock position. The new expansion tank fits neatly between the rad and air con pump. The NS HID ballasts sit between the wing and the TB feed.

 

]image

Edited by Terminator (see edit history)
Link to comment
Share on other sites

After getting the hang of 70mph wheel spin yesterday, my power steering pump has decided it has had enough. This is a TPITA, as it is two risky to take the car out and get stranded with no PS assistance. The pump sound terrible, it sound like the bearings have gone as the vanes in the pump can be heard hitting the inside of the pump housing. The car has to come off the road, until I can fit another. I would also like to rebuild my original pump and see if it can be uprated in some way. Totally gutted as everything was going so well.

Link to comment
Share on other sites

After getting the hang of 70mph wheel spin yesterday, my power steering pump has decided it has had enough. This is a TPITA, as it is two risky to take the car out and get stranded with no PS assistance. The pump sound terrible, it sound like the bearings have gone as the vanes in the pump can be heard hitting the inside of the pump housing. The car has to come off the road, until I can fit another. I would also like to rebuild my original pump and see if it can be uprated in some way. Totally gutted as everything was going so well.

 

I had exactly the same thing happen to mine after it was off the road for a few months while engine and turbos were installed.

 

Part number is 44320-14250 if it helps.

Link to comment
Share on other sites

I had exactly the same thing happen to mine after it was off the road for a few months while engine and turbos were installed.

 

Part number is 44320-14250 if it helps.

 

Thanks Nic, how much roughly? Arm and leg springs to mind:(

 

I think the thrust washer has probably worn. I can just move the pulley about 1/2 a mm. I will keep a spare from now on. I may try to modify the spare and see if that helps.

Link to comment
Share on other sites

you've done the right thing Termy i lost a hose off the P/S some years back and it dumped all the fluid over the car park at work, i drove it home about a mile with no P/S, big tyres, heavy front mounted engine = virtually undrivable :(, having had that experience i would never drive the car knowing the P/S pump was dodgy

Link to comment
Share on other sites

  • 2 weeks later...

The video in the post show the loudness in (uncalibrated) dbA, so these can not be seen as accurate figures. However they give a pretty good indication of the effectiveness of my totally custom 4” system. All the tests were carried out with the DB meter using the same sampling method, namely dbA which is apparently the measurement that most closely resembles the sound levels in the human ear. All measurements taken with the meter on a tripod at one metre from the exhaust tip and at an angle of 30 degree ( thanks Wez). The meter was set to record the highest db in each test. The maximum db hold was also selected to capture the highest db at 4000 rpm. With this custom system the car sounds just a little quieter than my previous HKS Hyper cat back system.

 

Just as a recap, the car has a GT74, 280 cams, 1mm over size valves, head porting, HKS manifold and a Jun style plenum attached to a Q45 throttle body, In the exhaust system there are two Borla race silencers and a Burns silencer as the back box.

 

image

Edited by Terminator (see edit history)
Link to comment
Share on other sites

This next clip, recorded with the Burns bung in place. There is an annoying buzz due to a loose bung fastening bolt. The deeper sounding rattle is the triple plate clutch. With the bung fitted the lower frequency notes are taken away so there are very few resonant frequencies in the cabin, the car sounds positively civilised. I have yet to repeat the tests with the db meter in the car, however to my ears the difference in car, sounds amazing. The Burns bung does a very good job.

 

 

image

Edited by Terminator (see edit history)
Link to comment
Share on other sites

The final clip my favourite, records the exhaust dbA levels at idle then briefly at 4000 rpm and finally up to 8000rpm. I think the pipe does an amazing job as the dbA only rises a couple of points over the additional 4000 rpm, still well under the requirements of many tracks.

 

image

Edited by Terminator (see edit history)
Link to comment
Share on other sites

That shot makes the turbo look as if it is almost touching the turret. There is a fair bit of clearance and so far it has not got close, even with some pretty violent up and down changes in the high rev range.

 

The exhaust note from 4000 onwards is amazing that clip does not do it any justice at all:D

 

The map is only up to 0.8bar at the moment, the power steering issues put a stop to any further mapping. The weather since sorting out the steering problem has not been conducive to 1.4 bar at WOT.

 

I just love the way the car drives now, even the 295's are OK in the wet, there are traction issues, but that is to be expected. I have not put RLTC back on the car yet, but so far I have not felt the need for it. It is great to be back in a manual again, the power is so much easier to control.

Link to comment
Share on other sites

We want to see how far we can push it on road fuel first, the high compression is a bit of an unknown. So far all temperatures have stayed the right side of all the gauges. EGT's in number six are far lower than my stock engined BPU auto at WOT, with the probe in cylinder number one. No road fuel target as yet, I have one for race fuel, but we will have to wait and see how it goes. I really want to get the prop loop fitted before we turn up the boost.

Edited by Terminator (see edit history)
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.