Rolling road setup

[ranj]

Since my rebuild i have melted 2 pistons due to det ... running 20psi on a gt28r and afr being on the rich side .... my head is 73mm. So this time i opted for a rolling road setup so i could play with ignition timing whilst having the operator listen for detonation.

Spent over 1 hours on the rollers and did 33 power runs to try to get the best out of my setup. The car produced 167.1 at the wheels on about 22psi (before carb) 17psi (manifold) which roughly eaquates to 200.4 Flywheel power i was told ... Will Put the Power runs up later. I am having to run about 8/10 degree of retard to get no detonation .... at this level of boost .... Not very good i know ... advancing timing kept on bringin on det .... also upping boost to 20psi ( manifold) was causing detting ... so for the moment its timing will stay where it is and so is boost.

One thing of concern from the operator was my inlet temps before the turbo ... they were about 60degrees so i need to somehow get more cold air onto filter. This will be my first step.

Thinking about trying a different renix unit incase mine is not running right and making me run excess retard. Also thinking about decreasing my main jet to a 125 from a 130 as the afrs are rich (1.4mm secondary i have) but worried about detonation.

Any other ideas about a route i could take ???

[Andrew Cooke]

sounds like your renix is fubar

[rs250nut]

What cooler are you using?

[ranj]

Im using a chargecooler and intercooler .... the air temps measured were before the turbo and the probe was put into the air filter ...

[rs250nut]

Im using a chargecooler and intercooler .... the air temps measured were before the turbo and the probe was put into the air filter ...

Correct me if im wrong but why would you want to measure temps before the turbo?

[ranj]

MMMMM thats what i thought .... i do have a gauge that measures temps in the carb ... but nt sure what thats was reading whilst on the rollers ....

[Os8472]

sounds like your renix is fubar

I agree, ya Renix fecking timing up, replace it and wind down the boost beofre you take it for a blast, then begin the setup process from scratch

[Rob@Backyardracing]

sounds like your renix is fubar

yup, second that.

have you tried sucking the aei tube? it should be solid, no leaking.
remember its a 20year old rubber diaphragm...

[rs250nut]

Where have you got the air filter sitting, next to the turbo?

[ranj]

Yep i have checked the vacum capsule ... have sucked the aei tube ... there is no leak ... chekced dump valve pipe too ... im sure there is no leaks .... can the aei still malfunction ?

[ranj]

The air filter sits straight off the turbo ... it does need it position looking at .... will pu pics up after work tonight.

[Os8472]

Yep i have checked the vacum capsule ... have sucked the aei tube ... there is no leak ... chekced dump valve pipe too ... im sure there is no leaks .... can the aei still malfunction ?

Mine did, being a ph1 my AEI sat directly above the turbo but the diaphragm didn't die, dunno what did actualy but as soon as I changed the AEI all the problems stopped.

Anyone round your way who could lend you thier AEI for 20mins while you try it?

[ranj]

I have a spare renix unit here mate , will probably leave the setup as it is and then try advancing the timing with the spare renix whislt on the rollers again listening for det and see what happens ....

Heres my graph from the rollers .... still got to scan the other one yet ... this one just shows boost , afrs and max wheel horsepower ....

[Jimmy_GTT]

Yep i have checked the vacum capsule ... have sucked the aei tube ... there is no leak ... chekced dump valve pipe too ... im sure there is no leaks .... can the aei still malfunction ?

What do you mean by sucking the tube? Only by mouth?
I'm pretty sure that it won't tell you if there is a very little leak in the membrane.
You can suck no more than 3-4 psi, but it will get 17psi from the turbo.

The good method to check it to get a big (50 ml) syringe, connect it directly to the vacuum membrane of the AEI push it at least half way. Keep it there for a while (some sec. just to be sure it keep the pressure) and when you release it it have to go back nearly to its original position.
(sorry if my english is not so good...)

Here is a good site (in french):
http://www.neo-tech.fr/aei-renix-off...e/kit-membrane

I've just fixed my friend's AEI...

[ranj]

Ahh ok .. i see what you are saying jimmy ... maybe could do with testing both renix units i have .....

Ok heres the power graph ...

[Andrew Cooke]

blimey, that's a lazy old turbo

[Jimmy_GTT]

Ahh ok .. i see what you are saying jimmy ... maybe could do with testing both renix units i have .....

Ok heres the power graph ...

Here is how I used to test it: (you do not have to connect the gauge)

[ranj]

Believe it or not its a GT28r roller bearing .... with a 0.49 back end .... so god knows how lazy it would be with the 0.64 back end .......

Wonder if the faulty renix and me retading ignition is making it even lazier ???

[Andrew Cooke]

Believe it or not its a GT28r roller bearing .... with a 0.49 back end .... so god knows how lazy it would be with the 0.64 back end .......

Wonder if the faulty renix and me retading ignition is making it even lazier ???

I was thinking that it looked lazier than my .64. Possibly a combination of retard, stupid rich fuelling, and maybe you have a leak? Have you pressure checked the inlet?

[Andrew Cooke]

i see in another thread that you have a Kent150, which is near as dammit the same as a Piper 300, did you time it in? Also, what compression are you seeing on a compression tester?

[ranj]

well the fueling is definately rich to begin with .... 1.4mm secondary and a 130 main at moment so was gonna knock main to 125 to see what effect that has ... but gonna change the renix first and then the jet ....

I had the valves checked and lapped in 500 miles ago so they should be fine ..... i did a compression test on saturday just to make sure everything was fine and i was seeing 145 to150 in all cylinders ... I also checked the cam timing when it was first setup .... needed to adjustment it was spot on ....

Possibly too much retard cos it looks about 10degrees ... else i was gettin det ... maybe due to renix .. will see what happens with other unit ...

[Andrew Cooke]

are you sure the lambda sensor was reading right? With AFR 10 you'll be seeing black smoke, and the engine will be fluffing.

[ranj]

I am not sure ....... there is no fluffing ... black smoke i dont know .... I am also running a lm2 and my readings on that are leaner than the rolling roads .... will check what that says at WOT in 3rd gear ....

[ranj]

Ok , Off again to the rollers again tomorrow with a different renix on the car .... the old unit seems to have no leaks ... but can still something go wrong on retarding/advancing ignition side of things ... ? One thing tho ... some oily stuff came out the renix vacum nozzle that was on the car .... Could that affect the unit ... ?

My lm2 shows 11.1 on full boost of 17psi .... But it is rather rich when i floor it and ask it too accelerate ... maybe 10.5 ish ...... Also at a set of lights in 1st gear and floored from standing start it does fluff a bit as afr reads 9.9 then its goes away as afrs increase .... Should i change main jet to 125 or leave it at 130 and change air corrector back to 1.1 instead of 0.9 ????

Anything else i could look at chenging before i go or am on the rollers ???

Thanks.

[dave j gtt]

As Andy said
Possibly a combination of retard, stupid rich fuelling, and maybe you have a leak? Have you pressure checked the inlet?


leak! you say you have a dump valve there could also be a leak there or in boost pipe runs.

If your turbo is as you say, from what andy has said it seems you maybe got a boost leak

[Rob@Backyardracing]

leave main std, your AC is alot more sensitve to fueling than a main jet, but i would rise this aswell...

[ranj]

I bleedin cant find my jets i had lying round ... typical ... so may just have to do power runs tomorrow on the different renix and see if can alter timing to more advnace than it is now ....

Still gonna see if i can find them jets tomorrow ... So maybe 120 main then and 1mm a/c ???

Leave secondary at 1.4mm ??

No leak in dump valve piping ... checked again ... no leak in boost hoses either ... will check again on rollers and see if i can hear anything ....

[ranj]

Just got in now from a session on the rollers ... I have made a few alterations to my car since its last visit ... I have Changed its air filter location , Changed the a/c jet to 1.2mm , and also put on a different renix unit ....

Ignition is running about 4degrees retarded now ... Intake Temperatures before turbo were 61 and now are 47 ... The ambient temperature was the same ... 21 ...

For some unknown reason to me the car is running 0.1bar more boost than before ... maybe temperature reduction i dont know ...

The power now on the last run is 185.6 at the wheels .. and flywheel power is estimated at 221.5 ( did hit 226 at one point) at a max peak boost of 1.6bar at carb top (makes 1 bar boost at about 4300rpm )...torque is about 204 ftlb .... Afrs are a lot better now ... mid to high 11s then leaning out to 12.2 ... maybe too lean but no det occuring ...

On the road the car is a lot more responsive ... and from the power curve it gains power all the way up from 3750rpm .... from about 4650r rpm it gains near enough 20bhp all the way up .... Will Post Graphs Up tomorrow ....

[Scoff]

Soods good ranj, not sure what needle you have in but be aware that you are probably at the point where the standard needle jet will want to lean off in higher gears.

[ranj]

Theres a 2mm needle valve in it ... My lm2 shows a weaker afr than his gauge on the rollers so will callibrate it again and check if anything alters .... Also asked him to do a fifth gear pull to check for any signs of det to be safe .... Funnily enough i was trying to get him to listen out for compressor surge ... but guess what it didnt happen on the 2 runs we did .... Typical ...

My carb is now at 2mm needle , 1.4 secondary , 1.2 a/c , 130main ... would have tried a different combo if i could have found my jets .... was gonna try 125 main and 1.0mm a/c ... dont know what that would have done .... Gonna leave things as they stand for now

[Scoff]

the 125/1.0 combo might have been a bit better for the off-boost stuff but who cares, it runs and isn't melting this time

remember though, 5th gear on the rollers isn't always going to be the same as 5th gear on the road, depending on how much load he had on the rollers. with the float bowl issue it's all about how long you keep the engine at w.o.t for.

[Jimmy_GTT]

Nice to hear that your car is getting better. Great results.
So now you only have a 4 degree retard? This can be reached by only swapping the wires of the VR sensor?
Where can I get a 2mm needle valve? Or can I modify the standard one?

[Scoff]

Nice to hear that your car is getting better. Great results.
So now you only have a 4 degree retard? This can be reached by only swapping the wires of the VR sensor?
Where can I get a 2mm needle valve? Or can I modify the standard one?

No, swapping wires would advance the timing.

[ranj]

http://cgi.ebay.de/Schwimmernadelven...d=p3286.c0.m14


This is where i got 2mm needle valve from ... you can modify yours by using a 2mm drill bit ... but it needs to seal properly under fuel pressure ... Your choice which way to go

[ranj]

the 125/1.0 combo might have been a bit better for the off-boost stuff but who cares, it runs and isn't melting this time

remember though, 5th gear on the rollers isn't always going to be the same as 5th gear on the road, depending on how much load he had on the rollers. with the float bowl issue it's all about how long you keep the engine at w.o.t for.

... not sure on load ..... what will happen when it empties .... missfire or will deonation begin ???

Hard to believe that 4 degrees of igniton retard could have maybe saved 2 melted pistons ... Taught me an important lesson ... Dont just change stuff and think it will be fine ... before you turn the boost up have a proper way of checking afrs AND also listening for DETONATION ! It only takes seconds to Melt a piston !

[Scoff]

Yes, 4 degrees can make all the difference. 2 degrees can, but you would never normally tune so close to detonation.

Re emptying, it wil just lean off, so in mild cases it can lean and cause damage. IE, not lean enough to misfire. Just keep an eye on the AFR in high gears.

[Jimmy_GTT]

No, swapping wires would advance the timing.

Okay. No I would like to know what is the factory default setting of this two wire?
So I have to make the timing sensor adjustable to be able to retard the ignition?

I'll check this link for the needle valve.

THX

[Alex]

Sounds like you've got the car sorted Ranj - well done. It seems to be making some damn good power aswell.

I'm going to be building up a carb over the next month or so, so I'll be at the stage you've just gone through! I think I'll be running a bit less boost than you though....

[ranj]

Ta alex .... Best of luck to you ... I would just advise that you can listen for detonation and measure afrs before you start upping the boost ....

[ranj]

Its been a long time to post my graphs sorry ......... Heres the graphs of before and after i made the above adjustments .... I have noticed its making more booost with no adjusemts to actuator .... can the colder intake temp show a higher boost reading ???

Red line is before adjustments .... and Blue line is now ...

The next decision is do i leave things as they are or push further .....

[Jimmy_GTT]

Just got in now from a session on the rollers ... I have made a few alterations to my car since its last visit ... I have Changed its air filter location , Changed the a/c jet to 1.2mm , and also put on a different renix unit ....

Ignition is running about 4degrees retarded now ... Intake Temperatures before turbo were 61 and now are 47 ... The ambient temperature was the same ... 21 ...

For some unknown reason to me the car is running 0.1bar more boost than before ... maybe temperature reduction i dont know ...

The power now on the last run is 185.6 at the wheels .. and flywheel power is estimated at 221.5 ( did hit 226 at one point) at a max peak boost of 1.6bar at carb top (makes 1 bar boost at about 4300rpm )...torque is about 204 ftlb .... Afrs are a lot better now ... mid to high 11s then leaning out to 12.2 ... maybe too lean but no det occuring ...

On the road the car is a lot more responsive ... and from the power curve it gains power all the way up from 3750rpm .... from about 4650r rpm it gains near enough 20bhp all the way up .... Will Post Graphs Up tomorrow ....

Ranj,

are you sure that this 185.6hps is measured on the wheels and not on the flywheel?
I was on a roller 2 days ago. And we have measured 124hps on the weels at 0.95 - 1bar pressure on the manifold. (which is about 1.2bar at carb top). Estimated flywheel power is around 150hps. And if I calculate it for a pressure which you are running on for me it is about 185hps but on the flywheel.
Here is my curve. It is compared with my older measurement when the car was on standard pressure, oe. turbo, but a bit overfueling.
(The two measurements are compared in a wrong order.)

[Scoff]

jimmy, looking at those torque curves I'd say you either have a small turbo in there, standard cam or both ? Ranj has a nice cam and a T28, so 220hp is about right for a good tune and 1.6bar in the manifold.

[Jimmy_GTT]

jimmy, looking at those torque curves I'd say you either have a small turbo in there, standard cam or both ? Ranj has a nice cam and a T28, so 220hp is about right for a good tune and 1.6bar in the manifold.

T2/T25 hybrid turbo and a K-tech cam.
He has written 1.6bar at carb top. Take it as 1.5@manifold.
And I don't hink that this pressure is enough for such a high power.

[Scoff]

Plenty of people have done it though jimmy, but I can see why you would think it wasn't likely. You'd be suprised what difference the bigger compressor and camshaft make.

With a BP285 cam (the k-tec is much milder) and a T3 compressor on the turbo, 220hp isn't that hard to make with a good tune. In the years gone by there have been plenty of quick GTT's making 220hp and running 110mph trap speed down the 1/4mile, and a lot of those have not ran more than 1.5bar. I've done it myself years ago, I've made 235hp on a reputable dyno at only 21psi. It took 7700rpm's to do it mind, that was with high compression, a T28 and a BP300 camshaft.

[Jimmy_GTT]

Plenty of people have done it though jimmy, but I can see why you would think it wasn't likely. You'd be suprised what difference the bigger compressor and camshaft make.

With a BP285 cam (the k-tec is much milder) and a T3 compressor on the turbo, 220hp isn't that hard to make with a good tune. In the years gone by there have been plenty of quick GTT's making 220hp and running 110mph trap speed down the 1/4mile, and a lot of those have not ran more than 1.5bar. I've done it myself years ago, I've made 235hp on a reputable dyno at only 21psi. It took 7700rpm's to do it mind, that was with high compression, a T28 and a BP300 camshaft.

But if you take a look at the power graph this 221.5hps is at 5700rpm.
I can accept that it is possible to get 220hps. But I think it is only possible over 7000rpm.
What kind of ignition modul have you used for that rev?

[Jimmy_GTT]

For such a turbo (T2/T25 hybrid, stage 4 @ GT Tuning, 360 bearing) what cam would fit the best?
What pressure can I use?

If my calculation are correct @1.5bar I could get 185-190hps with the current cam.

THX

[Scoff]

ah, then at only 5700rpm I agree that it seems odd.

the cam choice is all about how you want to drive the car. I think you could go a bit wilder with the camshaft, BP285 will work well with a full T25. I'd be expecting more like 200hp @ 1.5bar then.

[Jimmy_GTT]

ah, then at only 5700rpm I agree that it seems odd.

the cam choice is all about how you want to drive the car. I think you could go a bit wilder with the camshaft, BP285 will work well with a full T25. I'd be expecting more like 200hp @ 1.5bar then.

Thanks for the advise.

[ranj]

Sorry ... been of the net for a bit .... the boost of 1.6bar measured at the rolling road was at carb top cos thats where they plumbed the pipe in ...... me myself measure my boost at the manifold which is about 17/18 psi .... the turbo i use ia GT28r and the cam is a kent rt150 ..... i ahve adjusted the timimg on the sensor to about 5/6 degrees of retard .... Maybe going back there again to push boost further .... but i need to make a few adjustments to the carb ... so will see how we go ... i have made over 30 runs on the rollers at the same place and we never revved past 6000 on any run ...