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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 9:39 am 
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You should be close to the end of what the oem injector can do so high duty cycle. That flow rate sounds low. I know there are two types of injector and from memory the injectors in a mk3 should flow slightly more at around 250cc depending on pressure. I reckon better to run new current tech injectors rather than relying on 30 year old ones. You have the ecu to run what you want so you're not limited like a lot of people. An injector failure is very likely to be dire.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 10:28 am 
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Yes and I’m now fitting a fuel pressure sensor. Loss of fuel pressure = shutdown
Won’t help a buggered injector though. That’s why I’m putting in the lambda LC2 now. Sensors up the wazoo. I’ve decided everything will be controlling until I have faith in the power plant etc. the lambda won’t control mixture....just shut it down into limp mode if it’s not right.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 11:01 am 
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Good idea fitting the fuel pressure sensor. Logging the output could be really useful for problem solving, far more useful than a gauge on the reg.

It'll be interesting to see how the o2 sensor works out, they're not known for playing nicely with avgas.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 11:27 am 
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Hence the suggestion of running a Bluetooth OBDII diagnostic scanner. Easy way of out-putting all that sensor data to a tablet, so when you do test power runs down the road, you can see what is happening to the car.

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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 2:47 pm 
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Yes I like the tablet idea.

Yes Sam there is always a catch I guess.
Perhaps I’ll just monitor afr.

So what do you think about the exhaust manifold?

Also interesting website I found that may indicate my injectors are close to a 90% duty cycle.
Took a pic.its very close to what my setup is.

Now I did the flow checks prior to injector cleaning and a new pump I think...also the fuel filter was not done yet....perhaps I should get the flow figures from Chris...although I guess other points guys have made are still valid....reliability, age, spray pattern, new tech etc.

Btw....the flow should be higher....I don’t think I’d get the power we have from injectors only putting out 208cc per min. I have mark 3 injectors....it’s a mark 2 engine but the injectors are js29-1


Attachments:
File comment: Here is a 60% duty cycle. Maybe I should do the fuel rail and look for say 330 cc injectors? I know bugger all about this....comments?
BD1FD195-9CE5-40EE-B8CD-E9AD6A4DB9BC.png
BD1FD195-9CE5-40EE-B8CD-E9AD6A4DB9BC.png [ 507.8 KiB | Viewed 4 times ]
CD36A9F0-6480-4DF8-9BC4-ABB06918ABD8.png
CD36A9F0-6480-4DF8-9BC4-ABB06918ABD8.png [ 471.1 KiB | Viewed 5 times ]
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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 3:45 pm 
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You can do better than a web site to estimate the duty cycle, the ecu is able to log what it actually is. Check with your tuner and see if he logged it. If he hasn't then you might need to wait for it to be back in action to see what it is. There's a good chance he will have wanted to log it. 85% is about the safe maximum. If you're over this then calculate the % flow increase required to get the correct injector.

With the exhaust I'd make or buy a 4 into 1.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 3:51 pm 
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Thanks Sam. Reasons for the 4 into 1?

I have a really nice 4 into 1 merge collector sitting at home....I also have a manifold flange. Just need the bends.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 4:30 pm 
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You've got the bits and nothing else to do while you wait for the pistons.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 4:44 pm 
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Haha yup. Well I’m making the splitter....a front air dam....tweaking the brakes, going to Perth, then London, then Perth again and then London again and then Vancouver. So not a great deal of time...lol.

Yup I have most of the bits....guess I can at least try the four into one....after all....the engine is a revver and it doesn’t drop out of the torque range so prob won’t notice a lot of diff there.

Perhaps just mild steel....and ceramic coat? I don’t need brittle and shiny....what do you reckon?


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 5:08 pm 
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Yes, I agree just build it from mild steel and see how it goes. It would be a bit upsetting to make it in stainless only to find it wasn't quite right and a mk2 is required.

I reckon 4 into 1 because you've got the setup to stay in a fairly tight rev range. You know what the stock 4-2-1 gives so you'll be able to compare but I guess the engine will be a bit different.

I fitted an old 4 into 1 to my road car but after it cracked for the second time I put the stock manifold back on with a new 2 into 1 secondary. I reckon I can feel the decrease at the top end.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 6:26 pm 
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Yes I guess I’d just be concerned I might change the torque a bit but who knows....it might even be better with the tight rev range. Yep. I reckon I’ll go with the 4/1


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 8:43 pm 
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So what did you decide to do with your brakes?

You should be able to fit a disc of at least 11" maybe a bit more. Wilwood have a number between 10 and 11" with bolt-on hats that should work. Bolt-on hats should be easier to space the disc as there's plenty of offsets especially if you look at blanks. My setup is just under 10" as it was intended for 14" wheels so they're one piece which is not ideal. My calipers are 4 pot radial mount which is fine. You'd have to get a mount milled and that's probably the trickiest part. My setup still uses an oem master cylinder with bias although a pedal box might be a better option.

There was a guy from the states designing GTi mounts for Wilwood calipers he might be prepared to give you the cad file. That would make the job much easier provided you use the same setup as he did. As guess the gotcha will be the new swift uprights.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 24, 2018 9:02 pm 
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Actually just trying softer pads than the endless mx72 pads I have for the Suzuki sport calipers. No idea which ones yet....just want brakes to come on earlier....and stop better when cold.


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 Post subject: Re: Our little cultus racer
PostPosted: Tue Dec 25, 2018 6:59 am 
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Why not buy Mitch Graig's setup?

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 Post subject: Re: Our little cultus racer
PostPosted: Tue Dec 25, 2018 8:16 am 
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I don’t know who is Mitch?


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 Post subject: Re: Our little cultus racer
PostPosted: Sun Dec 30, 2018 11:30 pm 
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Well the rebuild begins again.

New parts ready to go in and some on order Still waiting for forgies for next four weeks is the main hold up.

Lambda, knock sensor, oil temp, fuel pressure sensors.
Fuel rail, injectors (need some ideas of brand and numbers here.....) braided fuel lines and AN 6 fittings.

Picked up 10 yards of Carbon. For the Splitter and I’m making front of car air dam with diffuser openings for rad and oil cooler. Louvres for air to exit from bonnet. Lower thermostat temp.
Larger aluminium sump in design...base flange made.

Mild steel 1.5” bends bought to make 4 into 1 header. Sam I looked for your pic but have not found it...where does your collector sit? Right under the sump? To hard to get bent up all in one go....so bends it is...lachie to tig them. Ceramic coating because close to oil cooler.

I’m hoping all this will sort the motor, cooling and monitoring issues. Plus get rid of the cast manifold that likes to leak and crack.


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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 31, 2018 11:47 am 
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swift12 wrote:
Actually just trying softer pads than the endless mx72 pads I have for the Suzuki sport calipers. No idea which ones yet....just want brakes to come on earlier....and stop better when cold.


Bigger booster or master cylinder? More pressure = more feel and stopping power. Ducted brakes?
I suppose you want a good balance between feel and stopping power.

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 Post subject: Re: Our little cultus racer
PostPosted: Mon Dec 31, 2018 9:18 pm 
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Been on a bigger MC....definitely not the way to go without a booster. Brake pedal like a rock and lower pressure to pads....we went back to the gti cylinder.


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 Post subject: Re: Our little cultus racer
PostPosted: Thu Jan 03, 2019 10:52 am 
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That's correct, the collector is pretty much straight under the sump :
Attachment:
IMG_5068.JPG
IMG_5068.JPG [ 1.45 MiB | Viewed 4 times ]


Mandrel bent one piece primaries would be ideal but you really need to get the shape correct first and then copy. I guess 1.5 dia given the cam is relatively mild. The following table ( from Graham Bell's book ) will give you an idea of length:
Attachment:
IMG_5069.JPG
IMG_5069.JPG [ 1.51 MiB | Viewed 5 times ]

With your injectors I'd see if you can log your current duty cycle and then calculate what you need. You could probably get the bits and build the rail while you're waiting. Bosch make a wide range of motorsport injectors and should make something that suits. They're around $100/injector. Ultrasonic cleaning and testing of used injectors is around $40.


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 Post subject: Re: Our little cultus racer
PostPosted: Thu Jan 03, 2019 3:23 pm 
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Thanks very much Sam.

I already had my gti injectors rebuilt....at more like $80 an injector!

I have been looking at AN 6 extrusion and fittings. Ample for 160 hp. But how do you seal the injectors to the head? The Bosch Motorsport ones have a larger bottom than the gti ones...the gti seals won’t be able to be used. I’m not sure but is it the outside of the sealing ring they are supposed to seal on? It seems the lower injector ones push into the seals in the head. Can anyone suggest an appropriate injector replacement part number with around 330 cc.?

I know the cams are 106 degrees centreline....ummm.....I don’t have the inlet opening etc figures?

I have 1.5” mandrel bends....I’ll make my own from the bends. No other way for me.


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