WS6 TA

$.02 more:

Maximum boost is sorta the picture book of turbo information. Nothing blatently incorrect, but a lot of opinion and 'rules of thumb' presented as absolute fact.

What you do with the information in there will work, but you probably won't understand what really is going on...

WS6 TA

Hum… that VE change is much greater then some SAE papers suggest, and I’ve regularly dealt with at least one engine combination which was built at 8.59:1 which I’ve built 2 just about identical engines with 10.55:1 and all 3 are just about indistinguishable at the track (I wish I had real engine dyno #’s, I do have chassis dyno #’s for two of them but I don’t believe them to be correct).

That would be interesting info to see if anyone has built an engine optimized for turbos that has higher the 100% VE #’s (I’ve got some strange thoughts about VE’s > 100% anyway… but that’s not really relevant). I suspect that if they have it was optimized for turbos with very large turbine sizes. I’m sure that there are engines out there with over 100% VE that have had turbos added.

I’m not sure that compression is all that relevant to the discussion. I would argue that combustion chamber, piston, intake port and camshaft designs have at least as big, if not a bigger impact on octane requirements/detonation then and outright static compression #. I’m sure that most of us have seen 8.5:1 engines that detonated NA and 12:1 engines that didn’t… I also know of more extreme examples from people that aren’t talking about what they’ve done. Didn’t some of the PHR Engine builder’s challenge engines have compressions in the 15-16:1 range?

I’m not going to play with it right now, but when I tinkered with it last night I did change the efficiency #’s manually as well as the other #’s that I bitched about and found that it didn’t change the output #’s on the applet. It wouldn’t even show the top 2 points (6500 & 7000rpm) on any of the smaller turbos, including the 50 trim. I’m starting to wonder if where it displays the points might have something to do with some interaction between the java console and the browser (I’m no programmer, haven’t done any of that since about ’88-92, things have changed a lot…)

To be blunt I’m going to stick to what I’ve already said: either will work, neither are what I would choose if I had my choice of everything out there and given the choice between those 2 I would choose the 60-1 (if cost was an issue and I still had to choose between those 2 I’d choose the 50trim, but if cost was really an issue I’d skip both and go with an HX35w off of a Cummins Dodge Ram)

Yes on the turbine size, but that’s not what I said, I said that more power at a lower boost pressure will require a bigger COMPRESSOR, and the rpm that the power/boost happens at has no effect on compressor size.

More CI or water to air would be ‘growing.’ Less overlap would have nothing to do with taking advantage of more boost. Less overlap (and later intake valve opening) helps you manage more exhaust back pressure from smaller turbines or not as well designed exhaust. In a well designed ‘race’ application if you need anything bigger then a deltagate for about 900hp or less to manage boost (prevent boost creep) then you’re probably running turbines that are too small or too restrictive a set of headers...

And yea, I’m an opinionated SOB…

Mindgame

Hey, at least we're all finally in agreement that n/a motors can make over 100% ve. Things are looking up.

-Mindgame

turb0racing

Compresion is relevent when taking about the ve if you have low cr you have a lower ve like i explained earlier "You dont only gain power from the higher squish when compresing the air/gas you also gain power because the vacume is stronger sucking and blowing the gasses into and out the engine".

The less overlap will resist the extra backpresure.
you said:
"Less overlap (and later intake valve opening) helps you manage more exhaust back pressure from smaller turbines or not as well designed exhaust"

If you think about it you are contradicting yourself, the more boost the more backpressure on the turbine you will have. and werent you saying before that youd make a low rpm power turbo engine well you need a ide lobe seperation because at low rpms the exhaust gas isnt moving as fast and reversion (reverse exhaust flow) is more likley to occur.

turb0racing

How do you quote people??

and 67LT1Bird are you geting all this

67LT1Bird

Oh yeah. I am following every word you guys are saying. I have just been staying in the background so as not to disrupt the flow.

67LT1Bird

You quote people by hitting the quote icon down in the lower right corner of the specific message. There, you will see the specific code you need to type to do each separate quote.


Oh, and I am not trying to be a post *****.

I have one quick question here concerning the turbo fast turbo map. Actually, I suppose it is about reading a turbo map in a twin turbo application. It appears to me like the program is figuring that you only have one turbo, which would put the boost range for the higher rpms outside of the graph of the turbo. Since I will be wanting to choose the best turbos for the job, I will need to know how to pick the turbo in the twin turbo setup. Does one figure the lbs air that will be flowed at a specific boost level, and divide that by two for the two turbos?

Also, I did notice that Maximum Boost is more concerned with the basics than the real meat. The meat is what I get here.

Jon

67LT1Bird

In playing with the turbomap program, http://www.turbofast.com.au/turbomap.html, I hope that I have answered my own question. I put 4 as the number of cylinders which at least plotted my numbers on the different charts. I know this is the simple way to do it, and will have to figure everything by paper in the end.

Also, please keep this going about obtaining the highest VE possible for a turbo engine.

turb0racing

Also ou can set it to 2 cylnders for quad turbos! this will further reduce lag by decreasing the reciprocating mass. it has been done before and you can even use 4 stock oem t3 turbos to make around 800 hp on a smalllblock any higher you will need the turbines cliped to allow more boost. Cliping allows more gas to flow out the same size turbine by removing some of the turbine blades.

67LT1Bird

Quad turbos would be quite cool for the wow factor and for the very fast spool up rate, except I am also quite conscious of my lack of space, and the increased weight of all these little goodies.

Would be kind of wicked looking, though.

I would also figure that the area under the torque and HP curves of such a monster would also be very impressive. Am I right?

Problem is, this is starting to drift away from ve. Just to keep the post alive to its purpose, do you guys basically agree that, by running a cam like turbo said, and by making it a 383 (or even a 3.750" crank with 4" bore , a 373?), then this motor will be feeding itself within the range of 80-89% efficiency while running a CR of 8 to 8.5:1? Don't worry, after playing with turbomap for a while, I have seen that the ve does not play as critical a role, but this motor is being built to make power as efficiently as possible.

Jon

turb0racing

Ok so like i said earlier building a turbo engine you will rarely get a 95-100 ve. More displacment is what you need to make more hp being in the same ve arena. So go at least with a 383 if not bigger like a 396 (I recently learned of) they use a 4.030 bore but a 3.875 stroke crank and 5.85 rods using 350 pistons. You can always build a 406 or like what monty built a 1200 hp 427 sbc You need money out your *** to build it exactly how he did im guesing here but his engine setup is around 30k in parts alone. Im building my turbo engine for 30 times less than him and im going to have around 400 hp with 10 lbs out of 267 ci so monty has 3 times morepower. But if i had the money id do it just as he did and get the best for everything only i would have built a 454 smallblock quad turbo.

Ok back to the subject :P

The bigger the engine the bigger the heads you can run and the less boost youl need to attain the ~1000 hp goal. The less boost will allow you to run a slightly higher c/r and will increase the ve by a few %. So the law of engine building still applys "Theres no replcment for displacment"

Il try to rember to send you the DD2000 cd tomorrow.

Do you get why turbo engines have wider lobe seperation and less exhaust duration? If you dont i can explain it all in one shot.

Tim S

GONG

go find yourself a definition of VE, as it seems you don't have a full grasp of it.