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Actually had a look back and the Hy35 I have had a 56 x 83 comp wheel put in with larger diameter crossover which is slightly bigger than the gt3582 comp wheel at 56 x 82 but stand to be corrected .
The first 16v I did used a k27/8 , now that probably was to small . David has a nice quick car at over 400hp with good intake tempatures , I would be happy with that . I probably dont have much more hp
but its enough for me.
The Holsets are not the most modern turbo but are cheap and work for me.
Would love some updates Patrick on how the car is comming back together.
Here's my hx35 with t3.82 housing and Hy35 with cerecoated crossover.
Hi Sherry - nice engine you have there.....one day I hope I will get round to converting my 8v to 16v.
Holsets are great performers and also great value 100% agree on that. Lots of people getting good results too.
You have to be careful comparing Holset wheels with Garrett wheels though as they are not the same. The inducer on the latest iteration of the 3582 is huge (66mm) and that compressor wheel is rated for 850hp. In Garrett world the inducer you have on the Holset is much smaller (56mm) and about 5 sizes of turbo down from the 3582. The problem is we are not comparing apples with apples Holset have very different ratios of inducer to exducer so comparing wheel sizes is not the way to go. But on compressor wheels (I think) the inducer is the closer comparison. Even the very early GT3582 (GT35) had a 61mm inducer and was rated for 600hp, it was basically the next step along in evolution from the Stage 5 turbo I suggested above.
The turbo was originally built by Emanuel Galossen and he told me that the hot side would be restrictive and I could just bolt a bigger one on, scallop the engine mount and modify the flange for the downpipe - thoughts?
Sorry I missed this bit.....I think I would just ditch the Holset as still probably too small for a 3.0 16v on the compressor side. I am sure it would drive fine but if you have to go to all the trouble of removing, reinstalling plus fab work, just get it fabbed for a Garrett housing and you can choose a turbo and test the two different housings. For street and lower boost the 0.63, for track and/ or higher boost the 0.82.
All depends on budget but if you are this far in just get the right turbo.
Thanks for the info Nick .
Cost a big factor when I get what I need from the holset . I’ll put it on a dyno soon and see what it does for interest .
Talking of turbo Tim , I have his quick rack fitted .
The other engine is due to go in a 924 hillclimb project I’m doing .
Thanks for the info Nick .
Cost a big factor when I get what I need from the holset . I’ll put it on a dyno soon and see what it does for interest .
Talking of turbo Tim , I have his quick rack fitted .
The other engine is due to go in a 924 hillclimb project I’m doing .
I'm not suggesting you should change your turbo, but depending on usage it is a good idea to check back pressure as it is an easy indication of whether the hot side is a restriction or not. Smaller compressors are not really an issue as that would show up in intake temps. Small hot sides/ turbines kill engines. A big compressor wheel combined with a small turbine is also bad news as the turbine efficiency is compromised and again you get back pressure issues. How any turbo performs in any given engine is trial and error, you just have to install it and take the measurements.
As always data is key. The more data points you have and the more you can log the better. Then you can make more informed decisions about what works for your particular engine in your car.
Other indicators that I have noticed on mine when the hot side is too small:
1. Very early spool up (this can be masked by other issues that are delaying spool)
2. Getting to a point on the dyno where you increase boost but power is not increasing above 5k, torque at lower rpm might still increase
3. Power figures that are down on expected
Not checked back pressures but running egt sensor which would give an indication of problems and all good .
If serious about 16v , I have good 968 head with good cams and variocam available for £600 , give it a go .
Not checked back pressures but running egt sensor which would give an indication of problems and all good .
If serious about 16v , I have good 968 head with good cams and variocam available for £600 , give it a go .
Thanks for the offer!
I have a low miles head on the shelf from my old 968 engine. It is not a parts issue, more that I have a working 8v that I have not finished playing with yet and very little time. Hopefully that head will get used in the next 3/4 years but we shall see....life often gets in the way of car projects it seems as they are not high on the priority list. ULEZ isn't helping matters either.
If I knew what I know now when I started I would have done 16v in the first place as a 3.0 is wasted on an 8v head....but hindsight is 20/20 as they say
Not checked back pressures but running egt sensor which would give an indication of problems and all good .
If serious about 16v , I have good 968 head with good cams and variocam available for £600 , give it a go .
What pistons, rods and bores are you running on these 16v engines?
In my experience EGT may suggest more about ignition and cam timing than back pressure. Cam timing is perhaps more of a beaten path on 8V engines with enough feedback available online but with a standard 968 top end the factory cam timing with a low-ish compression ratio does not work well, all other things being equal. It took me a while to find the correct cam timing setting, first with the 8V engine after fitting a short runner intake, and now with the 16V engine which was not produced in turbocharged form from the factory and no reliable "turbo setting" to start from.
The GTX3576R with a theoretical 64 lbs/min compressor should be on the limit with my 16V engine and this should first show in the inlet temp as Nick says. Notwithstanding intercooler performance it could be interesting to measure back pressure in the higher boost ranges depending how the mixture richens in the upper rpm range, as was the case on the 8V engine after hitting the 6k rpm wall no matter what, but isn't the case yet with the 16V engine which wants to rev beyond 7k rpm.
If the back pressure/boost ratio increases as I increase boost, which I doubt it will much, I still see little reason to move from a 0.82 to a 1.01 turbine housing which will not fit in the standard location as Duke had shown in the past and as the largest 1.01 housing would make more sense with a GTX3582R which may be too large and upset the excellent balance for a road car that I have been experiencing so far. I would expect power delivery with the '82 to make for an explosive and barely exploitable top end with a meager response down low. The '76 makes for an almost N/A engine power delivery which allows a controllable behaviour at modest boost levels thanks to a rather wide torque plateau starting at 4k rpm that seems to barely tail off beyond 6500 rpm, and with more than 16 psi of boost everything around processes so quickly that I would make no use of even more power.
One thing I would like to stress and that I have realised since running the 16V engine is that the turbo really is there to support how much the head can flow and is no more the major component which, for me at least, pretty much dictated how the 8V engine was going to drive. On the 16V engine the turbo is just there to support the performance of the head, and not the other way around. Very few of all off-the-shelf modern turbos will work with the odd misbalance between the poor head flow characteristics of the 944 8V heads which are installed on unusually large 2.5/2.7 short blocks. Holset turbos apparently work fine out of the box but considering they are mostly designed to work on truck engines which there again do not flow that much and have large capacity that says a lot about about much of a tractor design the 944 8V engine is. It can be made to work, but what a drag it can be, as most of us have found over the years.
Thanks Nick - a lot of useful info for me to decompress there.
Running a VEMS ECU, I think I’ll get some road miles on it “as-is” and enjoy the car over the summer but will wind the boost down to 14psi for a track day in the interim.
That Garrett Stage 5 turbo looks nice, I’d probably need it with the T04E housing as I struggle to fit a 3” inlet never mind a 4” as I’ve recommissioned the air con in my car - not sure how much of a handicap that would be? If you could send me the info of your UK guy for these then I’d really appreciate it - one to sit on the shelf until winter. I believe Sherry66 managed to remove his turbo from the car with the inlet manifold in situ too - challenge accepted.
Had both turbos out with intakes on david . I remember I tacked another nut on a flange on reinstall to make life easier if i had to do it again .
Nick the yellow one is a 3.25l stroker with top hat steel liners , eagle rods and ford probe pistons , its in process of being dry sumped .
The black cam cover one is the old hartech experimental engine with nicosil wet liners , carrilo rods and old coating wossner pistons
Would a dual wastegate mitigate issues with a smaller hot-side? Meaning the wastegate opens to keep back pressure in check. Not asking if it’s the right solution but is it a “bandaid”.
Would a dual wastegate mitigate issues with a smaller hot-side? Meaning the wastegate opens to keep back pressure in check. Not asking if it’s the right solution but is it a “bandaid”.
No it wouldnt help because same Cubic Feet per Minute (CFM) is the same, going through the same restriction.
Voith, I know there's a guy called Ryan who has fitted one of the EFR 7 series twin scrolls to his 3.2ltr 8v. Space wise you'd be dealing with a similar issue. They are definitely a large frame turbo. You could check out his thread in Pelican. http://forums.pelicanparts.com/porsc...fr-7163-a.html Probably has a thread in here too. Won't answer your 16v questions but might give a few tips for fitment.
His car is fast.
06-14-2023, 05:05 PM
