Nick Gough writes:
>Intercooler does more than cool the pressurized air for use with the fuel in
>the combustion process, thus giving significantly more hp than a non-i-cooled
>turbo. The heat comes from the turbo, where it can get *VERY* hot, thus the
>pressurized air would be hot going to the induction system.
>If the air were cool enough, an intercooler would not be needed.
Wait Nick, all the heat does NOT come from the turbo. Heat is a by-process of compressing a gas, in this case, air. (I hope the physicists among us will back me up on this.) Yes, some of the heat inherent in the incoming charged air is the result of thermal transfer from the hot exhaust to the turbo casing to the air but most of it is from the compression.
An intercooler is almost ALWAYS a benefit because of this. That is, air (gases) that are compressed will always heat up. By cooling the charged air, you run a denser mixture and can thereby help the volumetric efficiency of the engine.
Well, I've been biting my physicist tongue as the various misleading intercooler statements went by, but my self-control just failed.
Maj is right: compressing air makes it hot. (The air in the cylinder of a diesel engine is compressed so much that it gets hot enough to ignite the fuel oil). The air will also conductively and radiatively absorb some heat from the hot turbo assembly, but I don't know whether this is a large enough fraction of the total heating to be significant.
But *all* that an intercooler does is cool the air. Cool air is denser than hot air at the same pressure - that's all that's happening. It isn't a compressor, it's a passive heat exchanger, and it can't magically "increase the density". All it can do is remove heat.
(Actually, there is a small negative effect - there will be a pressure drop from the flow resistance of the air moving through the intercooler, and this *reduces* the density of the air coming out of the intercooler, slightly subtracting from the density gain caused by the temperature drop. )
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Greetings fellow turbo heads
I originally posted the question of a 740->240 intercooler transplant because original 240t intercoolers were a bit hard to find. I am currently in the process of fitting a 740 i/c core into my non-i/c 240, but I would recommend using a 240 i/c if you can find one. I was able to install the 740 core with only a few minor (but slightly funky) modifications - it's definitely not a stock fit. I don't currently have any connecting pipes so the i/c is not yet functional. I still haven't decided the best way to fabricate/obtain something suitable - so any advice in this area would be most welcome; I'm fairly sure (but not positive) that the stock pipes will not fit.
I'll send a more detailed description if people are interested -it's probably only a 1 day job to stick in the new (used) core, but having to fabricate the pipes w/ a few complex bends might be a bit of a pain.
> Greetings fellow turbo heads,
> I originally posted the question of a 740->240 intercooler
> transplant because original 240t intercoolers were a bit hard to find. I
> am currently in the process of fitting a 740 i/c core into my non-i/c
> 240, but I would recommend using a 240 i/c if you can find one. I was
> able to install the 740 core with only a few minor (but slightly funky)
> modifications - it's definitely not a stock fit. I don't currently have
> any connecting pipes so the i/c is not yet functional. I still haven't
> decided the best way to fabricate/obtain something suitable - so any
> advice in this area would be most welcome; I'm fairly sure (but not
> positive) that the stock pipes will not fit.
Chowder, er, turbo head #2 responds (lengthy treatise on installing an "aftermarket" intercooler):
This is a real interesting topic for me as I've been searching for an '84-5 245T mit I/C. (Gotta have that extra 40 ponies!) The search has been pretty fruitless (like the fruit trees I have in my backyard :=( ) as all of the models I've seen have been extremely high mile models or are outrageous in price. (I know, the age old dilemma..."Where to find a low mileage model for $3,000....) If there were some way for me to expand my search into the '82-3 model years, the pickings would be much easier. (Sorry, I'm rambling...)
There are a number of considerations on the retrofitting of a 740 I/C into the 240T models. The major of which you've outlined above. I think you've already done half of the major work, that is, the physical fitting and securing of the intercooler itself. Once in place however, I'd suspect that a certain amount of fabrication is going to be necessary to get it all working.
I think I can visualize two or three possibilities, most of which rely on your access to aircraft componentry :=(.
1) Obtain the requisite 3-4" i.d. aluminum tubing; have it mandrel bent to your specifications, e.g. intercooler to manifold inlet requires x bends at y degrees. Question is, who can bend pipe as such? Maybe a muffler shop but more likely, a race fabrication shop.
2. Use "pressure capable" rubber tubing such as that which is used to connect the aluminum duct work on existing factory turbo setups. Major drawback here is the availability of a hose material (at what cost?)
3. Combination of the two, above: Use what you can of the factory 700T plumbing and where it doesn't quite fit, finish with rubber hosing. (This seems the most plausible). I recall looking (and photographing) the underhood workings of Don Devendorf's IMSA championship Turbo Z car. It made extensive use of aircraft tubing (large diameter rubber as noted above) and under max vacuum (in the pits at least), the hosing did not show but a small trace of collapse.
4. The fourth alternative would be to have someone offer a retrofit kit much like what USED TO BE offered from the factory. All of the engineering would be done and all one would need to do is buy it and install it all. This sounds like a project my part-time partner and I would love to undertake were it worth our time and effort...) Anybody else out there looking to retrofit their 240 turbos with intercoolers?
In any event, this sounds like something that the aftermarket could really sink their teeth into. Heck, I'm surprised that no one has done this using readily available parts...think of all the non-I/C Volvos, Saabs, Chryslers etc. that could either be recipients of such kits...
I'd also wager that a number of other (non-Volvo) intercooler units could be used in place of the 700T units...they're pretty generic.
Just a few thoughts on the matter. Comments?
Thanks to all who responded w/ tips & encouragement regarding turbo plumbing (esp. M. Jue, D. Damouth,J. Matuszak & C. Corey). I had put off finishing this project due to laziness & the desire to spend time w/ spouse & kids. After being "reminded" & w/ some good suggestions I was able to install all the plumbing in about 3 hrs (9-midnight) last night. I had initially rejected the use of corrugated exhaust repair tubing because I thought it was too restrictive. Yesterday I was pleasantly surprised to find a large length of flexible "flat section" 2.25" diameter exhaust repair tubing at k-mart; this stuff was surprisingly smooth inside & slightly larger id than the stock pipes. I also used some 3" od, 2" id vacuum/pressure rubber tubing that I found in the lab to use as connectors-although the original volvo rubber connectors actually seem to work better (except the local volvo dealer wanted $20 each for them! what a rip!). Anyway, connecting the hoses was a snap - but it took me about 2 hours to make a bolt plate adapter to rotate the manifold inlet (it says "turbo" on it) so that it faces the front of the car rather than across the engine. I used a piece of scrap aluminum plate for this & precision machined :-) it w/ a hand drill, jigsaw & grinder.
Overall the installation looks very trick and professional, it was a hack job that was meant to be - the piping fits very well in the engine compartment w/ no interference.
Performance is relatively unchanged w/ respect to the non-i/c condition. However, I did climb under and disconnect the wastegate hose & fuel pump cutoff switch (for testing purposes only). I can now run the little boost guage about 1/4 of the way into the red before detonation - the power in this case is amazing. I'm sure I'm putting out 200+hp (using 93 octane) - but I'm still worried that this might be a bit much for this engine (is she going to blow captain?). I guess I have to reconnect the wastegate and set the actuator rod at some reasonable intermediate boost. Total cost, by the way , was about $170 - definitely a bargain if you like home brewed performance mods.
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>My '81 242 GLT is rated at 133 HP, .... I know most of the power
>increase is due to the intercooler (which my '81 does not have), but
>is that the only difference? Is there more boost? Different cam?
There are two things that make the intercooled turbos faster. One is the ability to run higher boost preasures without worrying about detination. The other is the cooling effect of the air/fuel charge itself from the intercooler. Simply put, the cooler (and hence more dense) the air that goes in, the more power you get out.
As far as I know, the cams are the same for the US delivery cars. European versions of all of the post 140 Volvos tended to get different cams.
>What's the cheapest way to get an intercooler on my '81?
I would check with rebutable recycled-Volvo places. I am also pretty sure IPD sells an intercooler. Scott Hart at IPD is very knowledgable in hotting up the 240 Turbos.
-- John Werner
> My '81 242 GLT is rated at 133 HP, 155 ft lb. Newer 240s
> using the same B21FT motor are rated at 162 HP, 187 ft lb.
Didn't know they still sold a 240GLT. In fact, I thought the only 240 sold was the GL? In fact, I was under the impression that the B21FT wasn't used anylonger, replaced by the B23FT?
The increase in torque is worth it.
> I know most of the power increase is due to the intercooler
> (which my '81 does not have), but is that the only difference?
Yes, well, at least my '84 GLT has the same basic configuration as your '81 B21FT, except for the intercooler (available on '84's and '85's).
> Is there more boost?
Yes. With the intercooler you get about 10.5 lbs over 3700 RPM. I don't see any reason why you couldn't kick it up to about 12 or 13.
> Different cam?
Not sure, but I don't think so. If you find out it is, please let me know.
>I think the compression ratio is the same at 7.5:1.
> What's the cheapest way to get an intercooler on my '81?
> Volvo still sells a kit, but they want $1000 for it. Are
> there any aftermarket kits? Has anybody done it from junkyard parts?
I recently tried to find a new intercooler and haven't had any luck (mine's leaking). Volvo's kit is overpriced by a LONG shot... a brand new intercooler from Volvo is about $400. You could then try to find the hoses and assorted parts from a junker. I would try to find a scrapped GLT int he junkyard first and get all the parts off it if the intercooler's already gone or toast and then get the intercooler from Volvo. Check the parts list.
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