is that on a T25 turbo?
is that on a T25 turbo?
That looks Huge
What size is the rear end of that then? .64?
Report from the rolling road
Scoff had just got into his stride he had her up to 223 bhp and 210 lb ft at 21 psi when we lost boost pressure. There was obviously a large leak in the boost circuit but we couldn't find it. The next customer arrived so I booked back in on the 5th March paid up and left for home.
The journey home was eventful as she started to really struggle on the motorway and I had to make a dash for the hard shoulder when I lost fuel pressure. I lost the brake servo so there was a clue where the leak was. By the time I reached home all sorts of weird pops and bangs back fires were going on and the idle raves were climbing.
On close inspection at home the throttle bodies had separated from the silicone hose joiners holding them onto the manifold. A wonder I got home really. Anyway a hours fiddling with some study jubilee clips and she is good to go again.
The only comment Scoff had was that the turbo spooled up much quicker.
Back to the pits tomorrow for some tweaking and look out for "Return to the Rolling Road" the sequel to come.
Brilliant update Russel. that's decent power too! I bet you cant wait to let it rip on full boost!
Sounds good mate!!! The relatively easy fix to the boost loss was a bonus too! 👍
A taster on YouTube of an early low boost run before the pipework came apart.
Ironically I think it might have been our efforts to hold it all together that put a strain on the silicone pipe connectors.
https://youtu.be/ubRs3MB9gHA
Awesome. 220bhp 210lbs @ 21psi. I can't see you going back now.
good power for mild boost. Hopefully when its all dialled in it drives and delivers its power well.
Good luck to you.
No doubt Russell. I think what I meant was, even after a couple of shakedowns this is already close enough to the old setup to ensure (I reckon), that you won't find yourself back on the carb. Not that I've got anything against the carb. I love it. I just think for your particular purposes EFI si the way forward.
Your right Trevor she feels like a beast start first pull in the cold so I'm hoping for some good news on the 5th. I was even worried that the engine would destroy the drive train.
Another eventful day on the rollers. This time the fan belt was thrown off. Scoff put it back on but we called it a day. He had practically finished.
The final figures were 222.4 bhp @ the flywheel and 211.2 Ibft torque.
The graph is here
https://www.rtoc.org/files/Technical%...s/Power%20.JPG
The comparison with the Solex is here. The Solex is in BLACK
https://www.rtoc.org/files/Technical%.../EFIvSolex.JPG
You can see there is more torque earlier on which is what I hopped for however ultimate power is down and that'a at a higher level of boost so somewhat disappointing.
Where as the carb was leaning out the EFI gives a very stable AFR.
So we have to fit a new fan belt Scoff had some tips to stop it coming off and I need to have a lip welded onto the throttle bodies to better locate the silicone hoses.
The first event for Doris the RenoYammy will be at Aintree on the 22nd April. That will be the real test (if its dry)
R
Looks like the experiment didn't really work then.
Considering that with the Big Jim Racing EFI inlet manifold on Phil Middletons Big Jim modified C1J, at Scoffs, was making over 300 BHP. I forget what the numbers were for your boost, all the pictures, graphs, data seem to have gone with the previous version of this site.
You probably need better shaped, shorter inlet runners to get the power. I presume being a medical GP you have sufficient money, so I don't know why you didn't just have some, many times tried and tested, Jenvey ITB's or something from someone who has proven credentials in this type of conversion for a track / hill climb / sprint car.
Good intel.
So there wasn't more to come after all. That's disappointing outcome, at least on paper. The graphs are very interesting. What a strange little blip at 2950-3300rpm that the carb makes which the EFI doesn't. Although EFI looks good 4000-4700 the headline from there on is simply weaker. I can only think it's due to the design of the inlet. I wonder if there's anything to be done in that respect.
Are you really liable to gain more power from simply running EFI though? More reliability and a smoother operation in general certainly, but more power, not necessarily!. What did Scoff mention? I guess its back to the drawing board to improve things, starting with the manifold I'd have to say. Why not contact our own Matt Rowley? He's making awesome looking inlet plenums/manifolds.
I'm not panicking she feels good on the road and from competition mid range torque is what you need. I'll see what happens in the real world.
On the carb she was leaning out dangerously, with the EFI, AFR are solid (I'll scan and post the graphs when I can)
I am pleased with the fuel set up having the swirl pot around the sender was asking for trouble and I got it but the fuel level in the swirl pot (registered by the standard fuel gauge ) is rock solid and I won't suffer fuel surge. I have just bought a fuel level sensor from a Chinese scooter to put into the tank and hopefully we will connect it up to the standard gauge and calibrate it and that will complete the fuel system.
Ian where is the fun in following the crowd? As you say I'm a medical doctor and I'm glad I made you happy.
What would be interesting would be to do a flow bench test of the standard inlet and your EFI one. That would at least rule out whether it is the new inlet causing the top end power to drop off? Maybe you have reached peak flow top end?
If you have less power for the same boost, then it has to be either pressure drop or IATs higher. If the AFRs are good. We're the boost pressure taken at the same place for both carb and EFI?
With EFI you should always gain a little as you can afford to be a bit on the leaner side (closer to 12.5AFR) as you know all cylinders are getting equal fuelling and need less of a safety margin. That is what I have found, if it is tuned to the same AFRs as the carb, then little will be gained by just adding the EFI alone.
At least no Pistons were melted are any other serious mishaps so certainly a good stepping stone.
Here is the comparison of boost and AFR for the Solex and the Yamaha TB's. You can see how boost builds earlier and faster with the TB's and the AFR is rock steady where the Solex leans out at the top end.
https://www.rtoc.org/files/Technical%...s/BoostAFR.JPG
Try fitting a partial baffle inside the plenum to divert the airflow towards each port, and put a radius on all of the inlets and outlets. You may find some more top end where air speed is higher with a baffle inside. A friend of mine did some flow bench tests on his inlet manifold which was a two into one design, and by fitting a partial baffle he went from 200CFM to around 320CFM. And gained more revs before power dropped off with less boost.
The boost pressure has been measured differently. For the solex it was taken fro the pipe to tthe MAP sensor so below the throttle butterfly and for the EFI it was taken from the fuel pressure regulator so off the plenum above the throttle butterfly. That would account at least some of the difference in the two plots of boost pressure.
Thanks for the info Matt that's a big change, we have trumpeted the plenum outlets and the curved design of the top of the plenum was hoped to guide the air towards them.
I nearly asked if the boost had been measured from the same place before/after.
It's going to be interesting to see what the comparative lap times look like and how it 'feels'.
Is that the equivalent of replacing the plenum with longer pipes? So at WOT there's a longer fast moving column of air rushing toward each inlet valve and building up some pressure until the valve opens? Rather that a reservoir or slow and swirling lower pressure air waiting to be suctioned into the next opening chamber?
The baffle is a way of helping direct the air, and reduce divide up the area where the air can become turbulent, but also not shrouding the ports too much so they can take the air they need without bias. It is not ideal, but worth doing if the plenum I'd going to stay the same shape. A tapered design plenum helps with keeping air speed up, so for optimising everything that is really the only way to go.
IT wouldn't effect the torque like if you were to add a length of pipe in there with a big trumpet on the end say.
Don't you think that a smaller turbo would better fit your mid range torque needs?
I've tried several one. This curve seems like a T25 which only gets alive after 4.000 - 4.500.
My best results so far are with the GT2056 which is more like the T2 and gives full boost much earlier.
i have to agree.Jim...I've gone back to a T2 on my GT with Efi and its much more responsive!
The problem with the GT2056 is the wastegate is tiny and needs porting out for stable boost.
have a search for the GT1752, it's a nice responsive turbo and good for plenty of power too.
Matty, you are right.
I did the porting as the WG was very small.
Spent this morning grinding a lip onto the base of my TB to better hold the silicone hose connector
Hopefully that should do it Russell.
She moves air like a storm in Florida
https://youtu.be/-mB4mqSQ1I4
The latest power run for Doris. The engine lost a head off an exhaust valve when I ran out of fuel at Aintree last time out. New turbo another head from Tony Hart at In Racing. Scoff at EFI Parts checks the mapping and.
Really good power that Russel! What boost is that at?
In your new head, have you gone for 1 piece valves? I guess your finding typical fatigue in standard items that are continuously used hard! Still testament of the standard equipment lasting reasonable prolonged abuse!
Also, how are the brakes now?
The valves are from Tony Hart and are 35mm which dont sit right into the valve pocket, which was a worry I dont know if they are 1 piece. I think the valve failed because I ran out of fuel as I headed for the finish at Aintree over 7K revs in 4th. I will be running with a larger safety margin in future and the pit crew have rigged the lifter pump from the reserve tank (that fills the swirl pot) to come on with the ECU so I can fill the swirl pot before starting the engine.
Boost pressures were 14.4, 18 and 23 psi
Some said that it would never work with the siamesed ports. I think we can say that it does work, at least reasonably well.
To recap twin throttle bodies from a Kawasaki ER 600, 5 O Black ops fuel injectors (https://www.fiveomotorsport.com/ )and a bespoke inlet manifold 1 TB to 2 inlet ports. ( https://www.youtube.com/watch?v=xlwBPscK5Nk)
Re the brakes Carbon Lorraine brake pads, just spectacular. They cost but what a difference they have made.
Last edited by RussellT; 11-08-2020 at 12:56.