Jump to content
SAU Community

Recommended Posts

iirc the IAT sender and the ecu coolant temp sender are the same, so it'd work as a IAT sensor.

But the problem is, you cant simply remove all the coolant temp compensations in the ecu. its used for general enrichment, cranking injection times, cold idle, overheating protection and cold timing protection.

have a look at the cranking injector times in the standard power fc map, theres a massive difference between hot and cold start. once you wire it up the way your saying it probably wont even start, let alone run properly.

  • Replies 139
  • Created
  • Last Reply

Top Posters In This Topic

iirc the IAT sender and the ecu coolant temp sender are the same, so it'd work as a IAT sensor.

But the problem is, you cant simply remove all the coolant temp compensations in the ecu. its used for general enrichment, cranking injection times, cold idle, overheating protection and cold timing protection.

have a look at the cranking injector times in the standard power fc map, theres a massive difference between hot and cold start. once you wire it up the way your saying it probably wont even start, let alone run properly.

Ahh yes you are right that there is more than the water temp correction to think of.

Acceleration enrichment is rpm dependent so it is not affected by the coolant sensor unless there is a water temp correction involved.

The cranking injection times are something to consider also. As you are aware these can be changed according to coolant temp. It is possible, under certain conditions, having the signal at 40 degrees when the engine is at 80 degrees could flood the engine.

In regard to cold idle I guess you would have to either disable the aac or put a switch on it. Then it could be a pain in the ass to start or at worse the mixture would be lean under whatever temp the sensor was reading, assuming that you used the coolant temp sensor as an air temp sensor. This could be resolved with the water temp correction..

My cold ign correction is all set to zero. I just don't flog my car when its cold, but you are correct in saying that is has dependency on the coolant sensor input. As far as overheating protection goes you would have to keep an eye on the aftermarket temp gauge. This would not affect the ecu tho.

I have altered my cranking ms times from stock. It is 25ms at 10 degrees and 14ms at 50 and 80 degrees. My car does start ok using even as high as 50ms at 80 degrees. Not that I would but it is just an example.

I think that it would be worth trying to use the coolant sensor for intake temp, although there is a high likelihood that the car would not end up satisfactory. I personally would try it as I can adjust everything for the swap. I would not recommend it to anyone that cannot do the work themselves and tune their own vehicle.

This seems to be one of those mods that is best achieved by using the right equipment in the first place, ie: a suitable ecu.

Another quick update. I got the car back from the exhaust shop today. I got a 3 inch mandrel bent dump made with a fitting for my wideband sensor. The guy did an excellent job and it was a fair price. The car is a lot quieter (dur) and has lost 3 psi from having the exhaust hooked up. Replacing the stock cat is next on the list. I have a manual boost tee so its all good. I haven't done much driving cos its peak hour so I'll make a little vid later when the missus gets home.

Lag. Yes there is lots of it and if I wasn't going to use the rb30 in the shed and eventually a put a 3.4L in it I would have bought a smaller and cheaper turbo. Still even off boost the car goes almost as good as my v6 vt commodore so I'm not complaining. There is almost no boost under 4000rpm. If I flatten it at low rpm I can get some boost down low but not much. At 4000 the car goes ok and at 4500 or so it goes spastic.I'll just make this clear now...In my opinion a gt35r is too big for an rb25det doing street duties. I can live with it tho and it wont be long before that lag drops over 1000rpm with the new motor.

I bought a new bolt type clamp for the part of the piping that keeps popping off and it held 16 psi. I will turn it up a little more tonight but I needed to get home and have a rest after work. Its been a long day. Oh btw the wastegate is f**king loud. Its a quiet car then its screaming its head off. ohmy.gif I'll be getting a screamer pipe plumbed into the exhaust next week or whenever.

Anyway rest now...

I think it should go pretty good with 3.4L tho. The torque off boost will be a lot nicer too.

I forgot to mention before about my tune. The afr's are still spot on and there was a max of 14 knock at any time. I'll get comfortable with the new power and find my preferred boost level then put it on the dyno. Give it a few weeks tho.

Great work mate! Sounding good. Yeah definitely pick up a 100 cell metal cat (I recommend from Venom), the stock cat will be restricting it a lot.

With a GT35 I would recommend a 3.5" outlet to the cat and then 3.5" from there onwards. 3" catback is too small for a GT35.

Ah yeah a 3.4L will definitely help with the spool hahaha, that will be unreal.

So I just made a little vid of going up the road and then to the pizza shop. Saw 20 psi, popped of the boost gauge hose and slipped the clutch in 3rd no.gif So much for a hd clutch...

The vid is a bit crap cos its dark and the camera isn't fixed. Anyway I'll upload it and it should be ready in half an hour yes.gif

I have a GT35 on my stock rb26 with poncams, i get 1 bar of boost by 4000rpm in 4th and full boost by around 4300rpm. I see that everyone looks at "lag" differently, to be honest i dont think my setup is laggy at all.

As for the exhaust side of things, Im running a 3" dump to a decat which is also 3" and the catback is 3.5". Setup is making 485hp at all 4 hubs on 20psi so my 3" dump is not a restriction :)

I feel comfortable knowing the 0.82rear housing is getting rid of all the heat at high rpm quickly as compared to a 0.63. I rather my engine breathe better than come on boost a few hundred rpm earlier!

To give you an idea on how much fuel you will need for a GT35 running 20pounds, my sard 700ccs are running at 89-92% with the stock FPR and an intank 044. Not sure on what my AFRS are though as i forgot to ask my tuner.

As for the RB34, or even an RB30 for that matter, id go a TO4z with a 1.0x housing, a 0.82 gt35 seems kinda small for an engine like that?

Edited by snozzle

I have a GT35 on my stock rb26 with poncams, i get 1 bar of boost by 4000rpm in 4th and full boost by around 4300rpm. I see that everyone looks at "lag" differently, to be honest i dont think my setup is laggy at all.

As for the exhaust side of things, Im running a 3" dump to a decat which is also 3" and the catback is 3.5". Setup is making 485hp at all 4 hubs on 20psi so my 3" dump is not a restriction :)

I feel comfortable knowing the 0.82rear housing is getting rid of all the heat at high rpm quickly as compared to a 0.63. I rather my engine breathe better than come on boost a few hundred rpm earlier!

To give you an idea on how much fuel you will need for a GT35 running 20pounds, my sard 700ccs are running at 89-92% with the stock FPR and an intank 044. Not sure on what my AFRS are though as i forgot to ask my tuner.

As for the RB34, or even an RB30 for that matter, id go a TO4z with a 1.0x housing, a 0.82 gt35 seems kinda small for an engine like that?

Hey man biggrin.gif I think the boost in my car comes on about 300 rpm later than yours but then I don't have cams and I'm down 100cc in capacity. I checked the injector duty cycle after giving it some at 20 psi and they were at 56%. I'm using 900cc @ 3bar jecs injectors.

I spoke to an engine builder here in Perth who has built rb's including a 7xxrwhp rb26 and he recommended the gt35r for a the rb30. It might be too small for the 3.4L but realistically I'd rather the turbo come on earlier and still be able to put out 500hp or so to the wheels.

About the exhaust, I asked the exhaust bloke about making me a bigger exhaust for the power I will make and he said 3 inch will be fine just delete the cat. So yeah a big cat is on the list. Right next to a new clutch sad.gif

Hey man biggrin.gif I think the boost in my car comes on about 300 rpm later than yours but then I don't have cams and I'm down 100cc in capacity. I checked the injector duty cycle after giving it some at 20 psi and they were at 56%. I'm using 900cc @ 3bar jecs injectors.

The 100cc difference in capacity is more like 60cc. It would make fark all difference, especially if you have VCT enabled and working properly. I think you will find that 300rpm is down to a restriction with the stock cat, will be interesting to see how it goes with a big high flow cat fitted. I know I picked up about 500rpm of response when I upgraded my cat and that was with the stock turbo.

Setup is making 485hp at all 4 hubs on 20psi so my 3" dump is not a restriction :)

Yeah I recommended a 3.5" catback as you already have.

How have you come to the conclusion that a 3" dump is not a restriction? Because its making good power?

Well i wasnt expecting any more power than the result i got and i got around 25hp jump from going 18 to 20psi, If the dump was a restricition id assume the increase in power would be less? Fuel system would be maxed out at around 510hp so the boost was capped at 20psi and tuner made sure there was plenty of fuel in there to keep my pistons happy :)

Edited by snozzle

Yeah dont get me wrong thats a tonne of power and it sounds like a heap of fun! Just providing some advice while the thread owner is getting his exhaust made up. I was spewing after I chose a smaller exhaust and then threw it out and went bigger. May as well go big straight up, especially with RB34 and a GT35!

I will be getting the exhaust replaced from the dump back next year. I'll get a cat before then tho. When I mentioned the clutch slipping it didn't just slip. It hit the limiter at 7600 as soon as it came on boost in 3rd. It's rooted now. I'll pull the box out and have a sus soon.

Yeah I recommended a 3.5" catback as you already have.

How have you come to the conclusion that a 3" dump is not a restriction? Because its making good power?

He has an external gate venting to atmosphere... Don't you have an internal gate? Totally different ball game when it comes to exhaust flow

http://www.youtube.c...h?v=cpyXkX7aeMo

Here is a quick shaky vid. Watch out for frequent swearing. After you see the clutch slip in 3rd cut to near the end where I show under the bonnet quickly.

14psi @ 4050rpm and 20psi @ 4400rpm.

Edited by Room42

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • That's odd, it works fine here. Try loading it on a different device or browser? It's Jack Phillips JDM, a Skyline wrecker in Victoria. Not the cheapest, but I have found them helpful to find obscure parts in AU. https://jpjdm.com/shop/index.php
    • Yeah. I second all of the above. The only way to see that sort of voltage is if something is generating it as a side effect of being f**ked up. The other thing you could do would be to put a load onto that 30V terminal, something like a brakelamp globe. See if it pulls the voltage away comepletely or if some or all of it stays there while loaded. Will give you something of an idea about how much danger it could cause.
    • I would say, you've got one hell of an underlying issue there. You're saying, coils were fully unplugged, and the fuse to that circuit was unplugged, and you measured 30v? Either something is giving you some WILD EMI, and that's an induced voltage, OR something is managing to backfeed, AND that something has problems. It could be something like the ECU if it takes power from there, and also gets power from another source IF there's an internal issue in the ECU. The way to check would be pull that fuse, unplug the coils, and then probe the ECU pins. However it could be something else doing it. Additionally, if it is something wired in, and that something is pulsing, IE a PWM circuit and it's an inductive load and doesnt have proper flyback protection, that would also do it. A possibility would be if you have something like a PWM fuel pump, it might be giving flyback voltages (dangerous to stuff!). I'd put the circuit back into its "broken" state, confirm the weird voltage is back, and then one by one unplug devices until that voltage disappears. That's a quick way to find an associated device. Otherwise I'd need to look at the wiring diagrams, and then understand any electrical mods done.   But you really should not be seeing the above issue, and really, it's indicating something is failing, and possibly why the fuse blew to begin with.
    • A lot of what you said there are fair observations and part of why I made that list, to make some of these things (like no advantage between the GSeries and GSeries II at PR2.4 in a lot of cases) however I'm not fully convinced by other comments.  One thing to bare in mind is that compressor flow maps are talking about MASS flow, in terms of the compressor side you shouldn't end up running more or less airflow vs another compressor map for the same advertised flow if all external environmental conditions are equivalent if the compressor efficiency is lower as that advertised mass flow takes that into consideration.   Once the intercooler becomes involved the in-plenum air temperature shouldn't be that different, either... the main thing that is likely to affect the end power is the final exhaust manifold pressure - which *WILL* go up when you run out of compressor efficiency when you run off the map earlier on the original G-Series versus G-Series II as you need to keep the gate shut to achieve similar airflow.    Also, how do you figure response based off surge line?  I've seen people claim that as an absolute fact before but am pretty sure I've seen compressors with worse surge lines actually "stand up" faster (and ironically be more likely to surge), I'm not super convinced - it's really a thing we won't easily be able to determine until people start using them.     There are some things on the maps that actually make me wonder if there is a chance that they may respond no worse... if not BETTER?!  which brings me to your next point... Why G2 have lower max rpm?  Really good question and I've been wondering about this too.  The maximum speed *AND* the compressor maps both look like what I'd normally expect if Garrett had extended the exducers out, but they claim the same inducer and exducer size for the whole range.   If you compare the speed lines between any G and G2 version the G2 speed lines support higher flow for the same compressor speed, kinda giving a pretty clear "better at pumping more air for the same speed" impression. Presumably the exducer includes any extended tip design instead of just the backplate, but nonetheless I'd love to see good pics/measurements of the G2 compressors as everything kinda points to something different about the exducer - specifically that it must be further out from the centerline, which means a lower rpm for the same max tip speed and often also results in higher pressure ratio efficiency, narrower maps, and often actually can result in better spool vs a smaller exducer for the same inducer size... no doubt partly due to the above phenomenon of needing less turbine speed to achieve the same airflow when using a smaller trim. Not sure if this is just camera angle or what, but this kinda looks interesting on the G35 990 compressor tips: Very interested to see what happens when people start testing these, and if we start getting more details about what's different.
×
×
  • Create New...