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  #1  
Old 01-03-2006, 01:50 PM
20vK 20vK is offline
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Default What kind of set up on a 1000bhp vw engine?

Hi boys and girls,

I've designed an engine based on the 1.8 20vt and I'm shifting enough air for a theoretical 1000bhp (1500cfm). Naturally, to attain anywhere near that level of power I'm going to have to reduce combustion temperatures. This will allow me to introduce more air and fuel to try and reach my goal. It is a 4 cyl. engine capable of up to 5 bar boost in the inlet plenum and runners. The throttle body is positioned directly on the end of the carbon fibre plenum. I will have a dual injector set up on each runner of the inlet manifold. ECU will be something like a MoTec m400.

What kind of WI factors do I need to consider for this setup? Naturally, my first concern is the hardware aspect. ie what kind of jets, how many, positioning, etc. What injection pump do I need to overcome manifold pressure and what pressure does it need to run at to give good spray pattern? Any thing really that you can think of.

And now for a very silly question: How much water / maths should I expect to use for this setup? I assume that Wi h20 consuption is based on combustion temps, but on high performance cars, when the inj is being used is there a generally accepted ratio for fuel:water/meths or air cfm:water/meths? I don't want to inject too much h20, so there must be an ideal ratio. If I know this, I can size a tank for WI, with respect to my fuel tank.

Thank you,

Rich
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Old 06-03-2006, 01:46 PM
20vK 20vK is offline
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Anyone?
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Old 06-03-2006, 02:32 PM
hotrod hotrod is offline
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The reason your not getting much response is that the information your asking for is covered in depth multiple times already here on the forum.
Spend some time with the search function and browsing the forms and I'm sure most all your questions will be answered.

WI is generally sized based on fuel usage, and fuel usage is always solidly tied to your power output.
Since you are clearly running a boosted engine I would suggest you take a look at the "Gasoline - Forced induction" forum.

This thead is also a good place to start --- it is a sticky on how to tune with WI.

http://www.aquamist.co.uk/phpBB2/viewtopic.php?t=457

Larry
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  #4  
Old 07-03-2006, 02:29 PM
max_torque max_torque is offline
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Surely someone with enough knowledge to design and make a 1000bhp 1.8 litre engine wouldn't need to ask around on the internet to find out how much water they need to inject??

suggest you try some basic thermodynamics theory! (ps. look up the bit about specific heat of evaporation!)

lol!
:roll:
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  #5  
Old 08-03-2006, 04:25 PM
20vK 20vK is offline
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Quote:
Originally Posted by hotrod
WI is generally sized based on fuel usage, and fuel usage is always solidly tied to your power output.
Thanks for the replies.

As you said yourself WI is generally based on fuel usage, which is why I asked about a 1000bhp engine. I didn't think 600 to 1000 bhp on a 1.8 would be included in the "general" classification. Being new to WI, I didn't know if the ratios would be reduced, increased or remain constant as power (and temperatures) went up, (could hydro locking become an issue, does the fuel:WI mix need to be leaned out / richened towards higher rpm and power levels, for example).

I did a search and couldn't find any information on injection pressures / injection pumps I should use when manifold pressure is up to a possible 5 bar. If I missed that, then sorry for wasting your time.

Having known nothing about cars 2 years ago, I reckon I have done pretty well to design an engine capable of this power range. The engine is based on solid theory, which I have picked up from 2 years of r & d, a large proportion of which was found on the internet. Most of the books I have read are based on lower power principals, which (as you well know) don't always apply to extreme examples. The fact that I have designed a possible 1000bhp engine does not mean I automatically know how to get rid of the heat it produces to actually run it reliably at that power level - that's why I am here. I would have thought that was obvious.

Yes, I have designed a unique engine. A large proportion of it is based on knowledge I have learned, but a large proportion is also based on "out the box" innovation. Just because I have designed something does not make me all knowing. That was why I went on this forum.

I am aware of the specific heat capacity of water and meths. Naturally, the amount to be injected depends on the mix ratio to be injected. I was hoping that someone with experiance of big hp engines (rather than someone leaning heavily on general principles), could tell me what did and did not work for them.

I read the link you gave me before I originally posted (thank you, anyway) but that still did not help me because the standard WI pump would not overcome potential manifold pressures I may experiance. There is no point investing in a pump that will never meet the demands of the engine it is meant to cool.

I'll have a look again, to see if I missed out on the answers I was looking for. But if anyone does have experiance with big hp WI, I would appreciate any information on how well your set-up works.

Thank you to Richard from Aquamist - it seems I require a modified pump capable of around a constant 10bar and between 600cc/min and 1500cc/min WI. If anyone could post a link to the modified pump section, that would be great. :wink:

Thank you, anyway

Rich
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Old 09-03-2006, 09:02 AM
JohnA JohnA is offline
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Quote:
Originally Posted by 20vK
..I didn't think 600 to 1000 bhp on a 1.8 would be included in the "general" classification. ...
You're right, it wouldn't.
Such an application would hit limits that others have not even come close - as you correctly suspect.

Since this is a virgin area (not much existing knowhow you can rely upon) why don't you start gradually, so you can catch issues as they emerge?
It's only natural to set it up reliably at 300bhp, then go for 400bhp, then 500bhp etc.
It won't be as cost-effective as getting it right first-time round at 1000bhp, but what you are doing is really R&D, isn't it?

What sort of static compression ratio are you intending to have?
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  #7  
Old 09-03-2006, 03:42 PM
20vK 20vK is offline
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Thanks, JohnA

Naturally, the mapping will start slowly. We'll get it running first and ensure all the usual stuff is working properly, as well as the boost management aspect I have designed. I would hope that no WI is required up to around 450 - 500 bhp, (as friends are achieving with their 20vt engines). If I got the design right, I shouldn't need WI up to around 600bhp.

After that, I think we'll need to cool combustion temperatures to achieve acceptable egt's.

Compression ratio really depends on results. I'll start at around 8.3:1 and see how things go. As you said, we're doing R & D on this new kind of design, so I think it is very much a "suck it and see" kind of approach. You can work with theory, up to a limit, and then all hell breaks loose!

Thanks for your reply,

Rich
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  #8  
Old 09-03-2006, 04:07 PM
JohnA JohnA is offline
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Quote:
Originally Posted by 20vK
Compression ratio really depends on results. I'll start at around 8.3:1 and see how things go. ..
true, but for a 800+bph 1.8 it might be wiser to start with 7:1.
Don't be shocked, the engine WILL run fine at such compression, it will just be a tad gutless while off-boost (it depends on the ignition timing as well)

You'd need specially made pistons for sure, with thicker crowns and a repositioned top ringland perhaps.
That would be the first deterrent against detonation. We're talking several bar boost pressure here.
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Old 13-03-2006, 05:00 PM
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Any idea where would be a good place to get pistons made up? I was going to use off the shelf forged items (easily available) to get the car running, and then switch over to the "ideal" CR pistons, once we know what limitations we're hitting. Boost can then be turned up accordingly, without destroying too much hardware!

Thanks,

Rich
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  #10  
Old 13-03-2006, 05:06 PM
JohnA JohnA is offline
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I'd contact piston manufacturers and ask if they can do it.
You may also have to forgo the squish band, but for such an extreme example it may now be just a 'nice to have'

I'd also avoid at all costs the technique where material is taken off the piston crown to make it lower. A thinner crown is not what you want on a 800hp 4cyl engine!
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