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To turbo or not to turbo, that's the question
coyoteboy - 18/7/16 at 10:48 AM

So I'm in the middle of cadding up my car and I'm in a moment of indecision. It's a V8 and I was planning to dump the 16kg intake manifold and run ITBs for the improvement in throttle response and, if I'm honest, the noise/look. But then I'm thinking I'd quite like to twin turbo it, and that will require much tighter packaging. And silencing of the itbs.

Would you trade off sound/looks for 150HP extra?


pekwah1 - 18/7/16 at 11:50 AM

What's the anticipated weight of this beast?

150hp "EXTRA".....!!!!

The extra power alone would be a fair amount in a 7 type or lightweight vehicle, so this thing would be nuts!


coyoteboy - 18/7/16 at 12:20 PM

Design target (and on-target just now with the parts I've made/bought and what I have in CAD) is 500kg dry without driver. In reality it will probably end up nearer 600. I'm thinking it might be suicidal with 450hp but I'd really like to push the 1000hp/ton mark just for bragging rights but I think it might just prove uncontrollable without 4WD.


pekwah1 - 18/7/16 at 12:50 PM

Considering what a 1300kg car feels like with 450hp, yes, it will rip your face off and throw you into a tree!!
But i would also be quite happy going out in style

Fair play to you, can't imagine if much of that will be usable but would be keen to see it!


ash_hammond - 18/7/16 at 12:51 PM

I'm over 300 hp per tonne and its more than enough in a 7. Things come up quickly and is enough to make your average passenger soil the pants. ;-)


coyoteboy - 18/7/16 at 02:17 PM

I'm a big fan of acceleration, less so high speed! I want this to rip my face off, but I don't want it to be undrivable. I think I might plan for accommodation of twin turbos but start off sane until I get used to it, or at least trust it more! I've got two 300+hp tin tops and it's going to be a terrifying step up from them, so let's just go sensible for now!

Moment of madness over. Or at least postponed!


prawnabie - 18/7/16 at 02:57 PM

Gas turbine feeding the turbos as per Nic Manns beattie?


coyoteboy - 18/7/16 at 03:05 PM

Don't tempt me. I'm really only in all of this for the engineering "can I do it"!


dave_424 - 18/7/16 at 03:14 PM

What v8 engine do you have in mind? I'm planning to turbo the 4L 1UZ-FE engine in an LS400, going big single rather than twin. Twin turbos require more pipework, more fabrication, more space etc.


coyoteboy - 18/7/16 at 05:39 PM

Audi ABZ (32v 4.2). Twin will be easier for me because the hot pipework will be going in already for the two banks heading rearward, single means joining them into one run. Cold side seems easier to deal with!
Will be scrapping the stock exhaust manifold, which are little better than a log lol


laptoprob - 18/7/16 at 07:10 PM

quote:
Originally posted by coyoteboy
So I'm in the middle of cadding up my car and I'm in a moment of indecision. It's a V8 and I was planning to dump the 16kg intake manifold and run ITBs for the improvement in throttle response and, if I'm honest, the noise/look. But then I'm thinking I'd quite like to twin turbo it, and that will require much tighter packaging. And silencing of the itbs.

Would you trade off sound/looks for 150HP extra?


More power??? Id do it in a heartbeat

All depends what its going in though as i nearly did the same in my Westfield then opted to go as much power as poss out of a Redtop instead of the C20LET and if im honest im glad i didnt in such a light car.


kb58 - 23/7/16 at 03:25 PM

After running a mid-mounted turbo Honda, my current thoughts are:
1. For the street, absolutely
2. For drag racing, sure
3. For track events, well...

To do #3 right requires a very well thought out system, preferably a dry sump, and a heavy duty cooling system in terms of both the radiator and intercooler. Most people cut corners on this and it bites them.

That said, if you're already starting with a V8, it takes very little boost to provide a big increase in power, so in *your* case I think you'll be fine. It's when running high boost on a small displacement engine that it takes a lot to keep it together.

[Edited on 7/23/16 by kb58]


ian locostzx9rc2 - 23/7/16 at 03:51 PM

My mate has a 5ltr v8 rover powered Westfield with 340hp weigh is 650kgs in a straight line its mighty quick but is terrible on bendy bits because the back just wants to step out and send you into trees so you can never use all the power so it's a waste at Santa pod he was doing 11.8 sec quarters were my zx9r powered striker was doing 13.5 sec quarters it is very quick but unusable most of the time seven style cars are great with revvy engines that you can use all all of the power my last striker with a Toyota 4age which was 140bhp in a car that was about 520 kgs was great on track embrassing much more powerful cars .


joneh - 23/7/16 at 05:17 PM

I'd be inclined to think that on the road or track an additional 150hp whacking in, especially out of a bend in a 500kg car will send you through the pearly gates on fire and backwards.


coyoteboy - 25/7/16 at 12:22 PM

I'm pretty used to humongous turbos punching an extra 110% onto the power output mid corner in other cars, but I agree it might be the end of me in this! Off-boost one of my tin tops is ~140hp, on-boost it hits 350 - between 2000RPM and 3000RPM.

My tin top is balancing on a knife edge of heat/det/boost (and recently fell off) so I'm well used to highly boosted low displacement engines but in this case a simple 6-7psi from a pair of barely-trying turbos should see a quick spool, low-engine-stress output and the engine is known good to about that level. Any more would need a fully build bottom end and I'm not going to do that, ever, due to costs. I'd be running intercoolers and I'll be runnign remote oil coolers anyway so nothing outside the current build plans bar the ICs.


[Edited on 25/7/16 by coyoteboy]