were back LOL throttle body zs

[tb steve]

Originally Posted by Ritchy

like the technical talk here just need snowy senior across here now

that would be fun i get the gist of all the tec talk but i could never do it my self lol

hi G
im off all week (should be if i dont get called in)

[Quadcam24]

Originally Posted by Drew

not the easiest to see, it got wet in the door pocket before i bought it!

steve's 200 v6. std manifold but the valves open, so short runners and large plenum with a single throttle body.



Drew

thats showing huge torque loss in the low and midrange, you can see where its missing !, compared to my last kv6 graph from reylands , which can be seen on xpf i believe. Mines showing 185ftlb at 3500, that ones showing about 147 !!....and wheres the power gone at 5800 revs, it should still be pulling strong up to at least 6500 revs, not tailing off !
In a zr i can imagine it would feel pretty quick but in a zs it would be gutless.


Imo the head will start to become a restriction at the power levels were talking about, put it this way , if you were to have them ported and polished etc you would see some gains....hence they must be restricting power.
Its good having free flowing intake and exhaust but if the actual engine is standard internally then it cant flow anymore air or make anymore power.
yes ross car made 260 on standard heads but thats with forced induction so you cant compare, it may have made 280 with head work for all we know.



edit, my last kv6 graph....click to enlarge, its the blue lines, red ones are the audi engine, before and after comparison on the same rollers.

[Maxxed_Ross]

there does seem to be a fair sized dip at the start of the graph... but from my limited experiance with mapping that could just as well be fueling issues

[Quadcam24]

possibly but this graph is the finshed job, if it had issues, then surely they would have been adressed and then the car re run and a better graph produced.

[Maxxed_Ross]

I say fuel as the only car I've been involved with mapping had a similar flat spot on the rev range, after spending quite alot of time at a supposed specialist. A bit of tweeking with fuel rates around the flat spot and it totally vanished.

I'm convinced some tuners just go after peak figures and forget about how the car feels lower down

[Drew]

that was track'n'road, if there was a flat spot they could tune out, it would have gone.

now that was a std manifold with no vis, and average exhaust manifolds as it was in a bubble. so results could have been better. but that doesnt mean it would have gained 30-40bhp from it!

depending on what revs these tb's are tuned at id expect to see a few lumps where the cams+tbs come on song.

Drew

[Drew]

just put a few graphs on dyno-plot if you want a comparison...
http://www.dyno-plot.co.uk/dyno/dynoplot/index.htm

Drew

[Eddie]

Steve had the bubble remapped and smoothed out a lot of the power, in fact, he done a fair amount of road mapping himself. When G built Steve’s bubble and had it mapped at PTS it was an unknown assortment of parts, the inlet was OE but PTS where unable to find an auxiliary to run the VIS system so mapped around them (left wide open), the exhaust manifold was made by Tony Law and in my opinion didn’t really suite the KV6 for making good power, just a very good OE replacement. Steve then insisted G use his very expensive back box and induction kit in the build, this limited power a lot (at the time). The car felt quick as it was in a lighter shell but in reality it went down POD in a 15 second quarter.
As I said in my last post, it’s OK to bolt on cams and exhaust manifolds which are designed for a stock KV6, you know what to expect, good punch of mid range with average top end gains. To increase on this you are looking at tuning the complete system from inlet to down pipe, remember, the engine is only an air pump, the more air you put “through” it (notice I never said “in”) the more power you’ll gain.
NASP tuning relies on flow, give an engine a massive gulp of air it will only digest what it’s internal components will allow (unless forced induction), increase the size of its throat (cams and ports) then it will swallow more, then increase its ability to digest that air (lungs) combination of compression ratio and exhaust manifold design it will consume the air with a mix of fuel and produce some power. Simplified yes, but NASP tuning rules are fairly basic, you can put in the same volume of air through 2 KV6’s and make each one produce its power in completely different ways, look at what happens when you replace the OE airbox for an induction kit, it flows more, this will only work up to a given point before the OE system will choke, some engine designs are very good from the factory and will have bolt on modification that promote power in different ways, low end with midrange punch or a lot or top end power, all down to the design of the parts installed.
IMO, Steve’s engine will maximise the potential of the exhaust manifold fitted, JS I believe, these have been proven to make good midrange power compared to say the H&S tuned system, there is a lot of research in manifold design’s for a good reason, what I do see is plenty of potential for development in the future, the induction and, injectors and management have been nailed, with increased compression ratio (pistons) with a cam profile and manifold matched for flow characteristics it will be interesting to see the results.

[Fred68]

I can't believe dumping the vis looses more then 20ftlb at lower rpms ? Does anybody remember the rover V8? It made 155 bhp in injected form and 212 ftlb of torque. But this had over a liter extra and two more cylinders !! The Kv6 may seem low on power but in real terms it's pretty good out the factory. If only it could be tuned as easily as the old V8!!

[Jay-ZS+]

Great post Eddie, as you say its all about choked or unchoked flow. Reducing flow losses to maximise volumetric efficiency. Guess I've learnt something this year.

Have heard that the KV6 heads are pretty good, would be good to get one on a flow bench and see some actual figures for them.