Inlet Temperature with Turbo car....

[neal1980]

Is it cooler the better really with inlet manifold temp. I mean using a front mount intercooler would get the temps down very well, but would it be worth using a charge cooler and water injection as well... or can you go too cool?

Thanks

Neal

[GreenV8S]

Cooler the better but you have to trade that off against pressure loss from the pipework/heat exchanger and extra intake volume (increasing lag).

[GavinPearson]

GreenV8S said:

Cooler the better but you have to trade that off against pressure loss from the pipework/heat exchanger and extra intake volume (increasing lag).

I second that.

[knighty]

yup, the cooler the air the more dense it is, therefore more air gets into the cylinders, and it drastically improves the volumetric efficiency, therefore more power......the common trap everyone falls into is fitting an intercooler the size of a barn door, then wondering why the throttle response is terrible, the trick now days seems to be a sensible sized inter cooler, well ducted to ensure the cooling air actually passes through the core and dosent just pour around the sides, and to include either/both internal and external water injection.

the external stuff is just like windscreen washer jets pointed at the cooling matrix, mounted in the bumper, and it squirts when you put your foot down.

Internal water jection is a bit more involved and requires a bit more set-up which is best done on a dyno, hence more expensive.

[CNHSS1]

would agree with Knighty, if you have a relatively small flow capability turbo or s/charger, stay away from 'bling' truck size I/Cs and huge diameter pipework. keep the pipe diameter sensible which will keep the air speed up at lower revs and maintains the response (spool on turbos) and really think about the pipe run lengths. make sure the I/C end tank shapes suit the pipe inlet angle too.

[Herman Toothrot]

One thing people have not mentioned is turbo sizing. No point winding a piddly little turbo up to 1.2 Bar if it leaves its effieciency range at 0.8 bar. It'll turn in to little more than heat gun. Decide what power you want then buy a turbo where that power lies slap bang in the middle of its efficiency range.

I'm a bit low down my turbos range at present pushing only 250bhp through one thats optimum is about 270bhp and peak 290, my inlet temps however, well basically ambient + 5deg c (also combining a good bar and plate front mount).

[chuntington101]

actually you can get the intake temps too cold!

there is a dyno car in oz that runs a dry ice box. even running a massive 106mm turbo on a 402 cubic inch LSX engine he still get intkae temps well below zero! fowever he you go much forthur you can run into problems. im guessing similar to the carb iceing days.

Chris.

[Mr Whippy]

Herman Toothrot said:

One thing people have not mentioned is turbo sizing. No point winding a piddly little turbo up to 1.2 Bar if it leaves its effieciency range at 0.8 bar. It'll turn in to little more than heat gun. Decide what power you want then buy a turbo where that power lies slap bang in the middle of its efficiency range.

I'm a bit low down my turbos range at present pushing only 250bhp through one thats optimum is about 270bhp and peak 290, my inlet temps however, well basically ambient + 5deg c (also combining a good bar and plate front mount).

I've plotted the P/R vs expected flow for my engine.

Standard the line sits pretty much right through the optimal efficiency line, but now I'm tuning it it's moving quite a way out of optimum efficiency at full desired boost/flow.

Is it that much of a bad thing?

Turbo is GT15, diesel, 4000-4500rpm 2.0, ~ 1.4bar from 2000-4500rpm if I can.

My brothers 306 1.9 Td recently ran on a K03 and had 1.3-1.4bar from 2000-4500rpm, and his intake temps still stay pretty low post intercooler (he has manifold temp sensor, and it stayed below 45-50degC on the dyno runs (was a bloody cold day, probably 0degC ambient)

Just not sure the efficiency is a huge problem, IF you are not intending to use the car flat out all the time!? Of course ragging a little K03 for 200bhp might be a bit much, but these little turbo's on diesels seem to spool up really well and give a good solid slug of boost when needed over their relatively narrow rpm range...


Not sure how well the bigger turbo's would respond, just to gain maybe 10% efficiency... when the intercooler is probably stone cold and ready for a spike in demand for cooling in normal road driving with the odd boost of power?


Still curious what is the best logic for good turbo matching on diesels I can't see an obvious practical downside to what I am doing... what are they ultimately?

Dave