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#61
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Yea, and $3K is cheap from what I've been researching. Ahh the joys of owning a shop Tom, I'm not 100% positive about the price as Andrew hasn't been disclosing such information to me however I suspect $1500 would be a safe mark to say and hopefully have it fall at or under that. Their stuff seems to run the 12-1700 range as is. I actually haven't talked to Andrew in a couple weeks as I've just been busy keeping on top of everything else here, as well as being down and out sick for a week or so. Damn germs......... And yes I'm working to develop it to be plug and play with the existing harness. That's what's making this so difficult right now as i could have just tossed on a 60-2 trigger and figured a few things out to make just about any old standalone work(I'd love to have OBR on this thing!!!) We're not entirely sure what will need to be done for the TCS yet, but in your case(and mine) that's a non issue as automatics are not in the picture on either of our two cars I'm looking to put forth some more time into this matter in a few weeks here. I just need to get on top of all the crap building up around this place and get some more money coming in. |
#62
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Here's how I see the twincharger stacking up as opposed to running a single supercharger, or running say twin turbos in parallel, like I used to have. The max CFM figure I gave you there is a maximum determinant based on the swept volume and speed of revolution, and the hp it creates is based on how much atmospheric oxygen that this one device can pressurise into the engine as a pump. [This maxes at 700 CFM and 18 psi like mentioned above.] Right. Now consider that the device, this twin screw blower is being supplied by air from the turbo that is pressurised to 1.4 bar, as opposed to 1 bar. This means that theoretically there is 1.4 times the oxygen in that air than there is in ambient, assuming we can efficiently extract the heat of compression. Now if we take it that the pd blower can deliver into the engine 700 CFM of this pressurised air with 1.4 times the oxygen in it, then the final horsepower calculation has to take this new level of oxygen into account. Just doing a rough calc with no special allowances for efficiency or temperature related losses, we could now expect to deliver 455hp, the old maximum for boosting up from atmospheric, multiplied by 1.4, the amount the turbo is pressurising the ambient air before going into the 1600. This gives a new possible engine output of 637, which is nicer. Bear in mind, of course, that there will be losses in the daisychain process, and keeping the charge cool enough will be the most important thing, both to get all the oxygen in there, and to keep cyl temps low enough to avoid detonation. Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#63
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whoa, a lot of text there. i just want to make sure I understand what you are saying.
W/o the twin charger an effectively cooler charge on the supercharger alone would yield 455hp if cooled and tuned properly. On the other hand, having a turbo that is effectively cooled running at a rate of 1.4:1 and also having effective cooling for the s/c this would result in a yield of 637hp. Just to make sure I am understanding you properly. It seemed to me earlier that you were saying that using the blower w/ or w/o a turbo would limit the engine's capability of making more power than the 455hp. Tom |
#64
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is the S/C limited though to an input charge of 1.4bar?
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Former: 1994 Barcelona Red(x2), 1995 Brilliant Red, 1992 Liquid Silver, 1992 Ebony(x2), 1992 Pearl White (x2) Current: 2017 Ford Raptor 2017 Kawasaki KLR 1995 Guards Red Carrera 1995 Spec-ish Miata - track car 1957 CJ-5 |
#65
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Joe now your talking, I agree with your last calc. Higher compression means more Oxygen per CFM of air. As regards effectency I think you will find that the twin boosting will generally be better if you have a large difference between the in & out pressures.
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1995 - SVX 700,000 K Mine, DMS Struts to lift car 2in. Tyres Wrangler Silent Armor 235/70R16, PBR Radiator. 6 speed with DCCD and R180 rer diff, Heavy duty top strut mounts front and rear. Speedo correction box fitted. New stero (gave up on the old one). Back seat removed and 2 spare tyres fitted for desert driving. ECUTune SC sitting in the box for the next SVX. 1992 - SVX 255 K Wife (Want to stay Married so not allowed to fit SC) 1992 - SVX Pearl with black roof race car roll cauge etc ready to race. Ex Tasman Targa car. 1995 - SVX Green low k mint condiation. 1995 - SVX Rally car, ex Matts car. Now to be used on track. 1992 - SVX red & Black being converted to Mid Engine. 1995 - SVX Red 143,000 bit rough. Owned 5 others Subaru back to a 1974 1400 GSR. |
#66
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As a commercial engineer I am aware that one should always do the sums especially including R&AD, along with design theory. I see no figures included relative to contingencies, e.g. pressure losses or in costing.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 02-19-2008 at 12:03 AM. Reason: hmmmmm |
#67
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No. In theory there is no limit, only what the turbo is able to deliver.
In practice the limit of what will actually work is imposed by the practicality of how much compression heat you can remove from the compressed charge. The more bars you give it, the more heat. If you can't get the heat out, then you are not getting the oxygen in, then you won't get the horsepower. Quote:
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Taking into account that in a real system there will be losses you need to take account that the above calculation assumed that the pre-blower intercooling was 100% efficient and no oxygen loss, this figure has also to be calculated downwards to real-world intercooler efficiency ratios. {This is partly the reason I kept the turbo figure low, Sicksubie, to make the intercooling work} If you re-calculate the post turbo intercooling to be a more reasonable 80%, the oxygen multiplier factor drops from 1.4 to about 1.15, this will be equivalent to 500 hp give or take one or two. Tom, considering your twincharger system is very, very sensitive to how much charge cooling you can pull off, you should genuinely consider adding cooling right now, using supercharger only. Cool the hell out of it and run it up to 17 lbs, you will get 450 hp no sweat. I like the twincharger idea though, but fabrication and efficient cooling will be your nightmare. It can work though, absolutely no doubt about that. Sorry about all the text. Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#68
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Joe I understand that fully. BUT I cannot run any more than 12psi without have a chrank pulley made the half the size of the engine. Not to mention that would be well over the efficency of the blower. I do plan on doing this in stages. Firts things first, i need to get my rod bearing replaced which has been stamped. Once that is taken care of I intend on following through with an end user programmable EM, most likely the hydra that Boxer6 is working for simplicity. Once those two things are up and running, the water/meth injection would be next to see how well this is actually working. I will have two EGT sensors and an intake temp sensor at that point as well to see what the cooling is actually doing. Once all is well with the supercharger and EMS, then I will be working on some form of a twin charger. The EMS will be tuned by a professional tuner, as I do not have the entire know how to do it myself or the facilities.
Tom |
#69
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Here is a chart that may interest you relating to the output of your 1600AX. [I was expecting you to be dropping to a smaller drive pulley on the blower rather than a bigger one on the crank, but I see what you are at OK] EG33 hp.....@psi... sc drive ratio... sc rpm 280 ......... 4.8 .... 1.21 ............... 6647 300.......... 6.3......1.30 ............... 7168 350 ........ 10.2 ... 1.54 ............... 8486 400 ........ 14.1.... 1.79 ............... 9827 440 ........ 17.3.... 1.98 ............... 10915 450 ........ 18.1.... 2.03................ 11189 Now as you already know I'm sure your twin screw is rated for continuous rpm of 13,500, and none of these outputs are anywhere near that. This gearing presumes that the EG 33 develops max hp around 5,500 for these numbers to make sense. When you get your Hydra and your sensors and your water/alky mist injection, set your pulleys for a ratio between 1.8 times and 2 times, and you will definitely get over 400 horse. With no strain on the blower!! Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#70
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I am already at an incredibly small s/c pulley because of hood clearances so I cannot go smaller in the regard. Only larger on the crank, which with my belt routing is not possible so I am restricted to 12psi. Like I said it will be a one step at a time process but I am looking to the future for goals. First things first, the engine needs to be done. The block should be taken down and go back to the machine shop in two weeks... Then I will work from there.
Tom |
#71
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But have you thought about maybe a cowled hood setup or a raised "bubble" over where the pulley would b, similar to how a DSM eclipse has that hump on that one section of the hood to allow some hood clearances for the turbo models?
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Tim 92 Liquid Silver SVX 5MT 2009 BMW Z4 (Gone) 2012 Camry V6 SE |
#72
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But Tim, if he is already using the smallest possible pulley on the SC because of hood clearance, then there is no way he can go to smaller to gear up the twin screw drive.
To make it spin faster, he can only provide a bigger drive pulley from the crank, and it's safe to assume from what he says he has not the room to maneuvre there, and it could not impinge on the hood even if he was able to go large with the drive pulley. Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
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