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Gtir Motorsport club » Gallery » Projects » My VET Build

My VET Build

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101 Re: My VET Build on 1st January 2017, 12:08 pm

ducie54

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Yes I've set the rev limit to 4500rpm as I'm still setting up software features, can't see the point of half doing things.

To set up VVL correctly you need to watch the torque on the dyno. So switch points could be anywhere as there's so many variables.

I'm running the LINKG4+ Thunder ECU which controls everything.

102 Re: My VET Build on 2nd February 2017, 7:01 am

ducie54

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Best i can achieve so far still yet to put it on dyno. IAT is killing me, its so hot here atm.

GTX3076r .82AR        3RD gear 2500 rpm start.  

17PSI @ 4300 rpm

103 Re: My VET Build on 2nd February 2017, 10:18 am

gtir_woody

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moderator
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Nice to start seeing some number, it has been really hot lately

104 Re: My VET Build on 23rd March 2017, 6:12 am

ducie54

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Spent the last month redoing my fuel system. It was drawing too many amps at idle as the pump could not be Pulse Width Modulated plus loud. Fitted a Walbro 255 as a lift pump and a Walbro 450 as the main pump. Also using a voltage booster to up the voltage to the main pump to get the flow i may require once i turn up the boost. Also bought a better quality PWM controller at runs at a lot higher Hz

My old surge tank was in the rear bumper area. Design was a bit of a compromise so this time i went stealth. Surge tank is now inside the main tank, holds just under 2 liters and all the return fuel is captured inside so the lift pump does not have to be so big. To get the volume i wanted with the shit gtir fuel tank design i had to make the surge tank from 2 pieces. Plus the lift pump had to have a separate mounting.

Will be curious to see if this new design helps with fuel temp as it was normally around 50C here in summer.







105 Re: My VET Build on 23rd March 2017, 6:17 am

johnny gtir

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Very good I have a in tank one not sure how much it holds but stopped all my surge even on track

106 Re: My VET Build on 23rd March 2017, 7:51 am

ADSgtir


Great build and you have thought through many things , the one area that I can see causing you problems in the longer term and because your set up is unique .
Sorry this will cost you some more bucks ;
The block and the head are relatively small for the amount of power (read heat) that you will generate ,at high rpms (heat cycles) , the heat to water system and heat to oil system need to be improved and you need data to work to :
A cylinder head temp indication would give you useful data ,thermcouple at the base of the plug(s) and a guage (you can get a multi channel) , you can now set a critical max temp , they are not expensive compared to what you already spent.
I have never had much success with electric water pumps ,they have always proved problematic and not predictive , I have had sucess using twin external thermostats .
using 2 external remote stats in parrallel , this doubles the available stat area and water flow for head cooling . If you wish to remain electric pumped then the BMW electrical control thermostats can allow a predictive cooling driven from the ecu , provided area is large enough to flow.
Oil cooling , the back up to the water cooling ,I guess you are using an air to oil cooler , I prefer a laminova water to oil cooler , they are very compact and easy to install and offer a choice of cooling medium with control -its much much cheaper than any dry sump with external temp control , and im stingy .
Fuel pump wise ive used a "boost a pump" for 3 years running 18 volts on boost and never had any problems what so ever , well made piece of kit and not expensive , easy fit ,t eed into a boost line.
I have in the past used a jag v12 fuel cooler ,its in line and simple fit , originally connected to the air con return feed , told you I was stingy -lol
A most excellent project , well done , hats off

107 Re: My VET Build on 23rd March 2017, 9:27 am

ducie54

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I have no doubts my cooling is capable for the task, cores were designed by one of the best in Australia. The 16" thermo fan moves some air too

I cant see the point of running cylinder head temp probes if im already using EGT's.

Davies Craig electric water pumps seem to have a good following over here, I guess there only as good as the controller used tho. Im using a solid state relay to PWM the pump and a 3D table in the ECU to set the DC% at any given RPM/temp. Using a 115 liter pump should flow plenty for the hot/humid climate here in North Queensland.

A laminova water to oil cooler will only reduce oil temp at a rate compared to water temp. A air to oil cooler is always going to have a greater difference in temp so theoretically should bring temp down quicker as long as it has good air flow. And to top it off mine has a fan on it.

I was lucky with the MSD fuel pump voltage booster in that i can set the voltage at 16 Volts with no boost line required. Saves me running another line to the front of the car.

108 Re: My VET Build on 23rd March 2017, 9:31 am

ducie54

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@johnny gtir wrote:Very good I have a in tank one not sure how much it holds but stopped all my surge even on track

Would of been nice if from factory they improved the internal design.

109 Re: My VET Build on 23rd March 2017, 9:47 am

ducie54

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Also had to modify the fuel tank cap. Factory electrical plug for the fuel pump needed upgrading due to the higher current draw of the Walbro pump. Used two bulkhead terminals for the main pump and the factory plug for the lift pump. The stock main fuel line in the cap was only 5/16 and the outlet from the Walbro is closer to 3/8 so i run a Dash 6 bulkhead. Will blank the std fuel outlet barb fitting. Also drilled out the return hole to reduce the amount being bypassed out the side and the return line pressure.

 


110 Re: My VET Build on 23rd March 2017, 2:20 pm

Mr B

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gtir technician
gtir technician
All looks to fit nicely, is way to go with internal surge tank. something need do to mine, the uk designed one was quite a clever idea .

111 Re: My VET Build on 23rd March 2017, 3:23 pm

johnny gtir

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That the same as the sunny Gti mate as that has basic one

112 Re: My VET Build on 23rd March 2017, 4:21 pm

ADSgtir


The EGT will give you the combustion cylinder thermal picture , so you can make adjustments to mixture to a max EGT or see the effects combustion wise .
The CHT will give you the cylinder head thermal loading , now you can see the rich / lean effect on the head and the cooling system efficiency
The stock head has its coolant passageways , designed around a maximum designed thermal capacity , areas in the head require more heat extracted ,and hot spots avoided .
The head is tested at manufacture and using various pressures and flow of water the cooling system can be sized - sized for pressure and most importantly flow .
Pressure has a limit as aeration occurs , air bubbles are disaster for cooling and the water must pass at a controlled rate. Some leeway is given for say low water quantity , oil quantity etc .
All the data is done around stock power levels and stock heat transfer , so what happens if you multiply that power by 3 or 4
There is extra capacity for this , if flow is increased . The problem is we only measure at one point , the water temp entering the head - this is not CHT , but the water temp .
Once water system is fully loaded (for that flow rate) it cannot absorb any more heat , so heat now passes to the oil system and oil temp rises .
This hides what is happening to the cylinder head internally temp wise and everything is on a delayed cycle .
A £50 CHT guage shows you what's happening to the head very quickly .
As cooling is a flow based system , fixed quantity of water , fixed rad size , variable pump speed and variable stat flow - the radiator has a very minimal effect as does the quantity of water .
Flow has a massive effect - take the stat out and the engine runs mega cold , so we have capacity for cooling , it's just the control of it .
Most people simply fit an oil cooler and accept that the oil has gone up by 30 degrees but the cooler has sorted that , it's because the water has maxed out on cooling that the oil temp rose , and now your CHT has also shot up - but by how much ? - CHT gauge.
Is it all worth it ?
Heads get valve guide wear, exhaust valves burnt,cracks around the spark plug holes,valve seat wear , warpage and gasket problems,hotspots and detonation all through excessive heat - it's all Dollar to a stingy bugger like me - lol

113 Re: My VET Build on 23rd March 2017, 6:36 pm

gtir_woody

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That's a good idea with the fitting mate. I wanted to look how to replace the inlet/ outlet fittings on the cap so I could run braided lines the whole way.

114 Re: My VET Build on 23rd March 2017, 8:44 pm

ducie54

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Again I'm not worried, my head apparently has the largest volume of water in the head of all sr20 heads. I suppose that's why it uses long thread spark plugs.

Water temp is measured on the outlet of the head not the inlet. If you were worried about aeration you would increase the system pressure or run waterless coolant. Simple fix.

I've used head temp sensors before, that was on a 2 stroke Go kart tho. When we went water cooled we swapped to EGT. I'd be more inclined to run combustion pressure sensors but there far from cheap.

115 Re: My VET Build on 25th March 2017, 12:17 pm

ADSgtir


As a guess : Nissan were worried about creep and permanent deformation of the head , so they specced a high quality aluminium alloy with good creep resistance .
However the alloy used had reduced thermal properties in heat transfer , along with the increase in creep resistance - the solution was to make the water jacket larger to compensate .
Nissan were obviously concerned over heat temps - just a thought .
Whatever great project

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