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  #61  
Old 02-18-2008, 12:56 PM
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Originally Posted by TomsSVX View Post
Ouch O-scopes are teh Expensive!!!... No rush either, I am still absorbing the costs of setting up my shop and am burrying myself in work to try and pay the bills... so I feel your pain. I do need to ask again, what the expected price tag is and it will be plug and play correct?

Tom

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.
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  #62  
Old 02-18-2008, 01:20 PM
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Quote:
Originally Posted by TomsSVX View Post
to be honest, if this is indeed the case it would not be worth while. I am having a hard time wrapping my head around that though. I can see that being the case at atmospheric pressure.

Tom
I'm the same Tom as regards getting the head around the concepts.

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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  #63  
Old 02-18-2008, 01:37 PM
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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
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  #64  
Old 02-18-2008, 01:48 PM
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is the S/C limited though to an input charge of 1.4bar?
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  #65  
Old 02-18-2008, 10:00 PM
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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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  #66  
Old 02-18-2008, 11:46 PM
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Worth it? You have had a guts full with the SC, and did not really sort it so is adding to the complexity involved going to drive you up the wall???????? Frankly on several counts, no IMHO.
Tom, I think your opening hmmmmmmm, says a lot.

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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Last edited by Trevor; 02-19-2008 at 12:03 AM. Reason: hmmmmm
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  #67  
Old 02-19-2008, 03:08 AM
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Quote:
Originally Posted by sicksubie View Post
is the S/C limited though to an input charge of 1.4bar?
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.


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Originally Posted by TomsSVX View Post
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.
That's correct. However, I have had another look at the calculations and I have a revision on this hp figure to 440. Graham is using a higher maximum pressure figure for the 1600 of 18.5 psi. Based on the chart I'm not happy with this. You Tom are using a conservative 12 lbs. This also is incorrect, too low. The usable figure is 1.8 pressure ratio, which adds [or boosts, if you prefer] 17 psi. 17 psi yields 440 hp from the EG33 at 80% intercooling efficiency.

Quote:
Originally Posted by TomsSVX View Post
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.

Tom
Yes, I believe this is correct, but needs to be adjusted as above, and is a theoretical maximum. I did mention it was a simple calculation, with no factors for inefficiencies added in, as Trevor correctly cautions. The figure of 637 above is based on the 455. Recalibrated to 440 and the more reasonable boost it should read 616 hp.

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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  #68  
Old 02-19-2008, 06:26 AM
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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
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  #69  
Old 02-19-2008, 07:17 AM
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Quote:
Originally Posted by TomsSVX View Post
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
Excellent Tom. You are working incrementally, then moving on, that's the way to do it.
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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  #70  
Old 02-19-2008, 09:48 AM
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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
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  #71  
Old 02-19-2008, 10:00 AM
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Quote:
Originally Posted by TomsSVX View Post
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
I know you said you wouldn't consider cutting a hole in your hood for clearance ,

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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  #72  
Old 02-19-2008, 10:09 AM
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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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