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Why the lower effect on US 240 Turbo?

FyoDisco

New member
Joined
Nov 14, 2020
Location
Sweden
There are probably a lot of threads with answers to this question, but I cannot find them. I have a 1982 Volvo 245 Turbo imported from the US and so it has a B21FT with the original 127 horsepower (or something like that). I wonder why it differs from the B21ET with 155 horsepower. Is it because of the catalytic converter the B21FT has or is it because of something else?

Thanks for your help!
 
The B21FT ran about 6 psi of boost. The B21ET ran about 9 psi. If Wikipedia is to be believed but it has no source cited for those numbers. I am inclined to believe the ANU physics article on engine specifications which states a similar 3-ish psi difference. So that is a contributing factor. Both had the same 7.5:1 compression ratio unlike the later turbo motors where the E got 9.0:1 and the F got 8.7:1.

https://en.wikipedia.org/wiki/Volvo_Redblock_Engine

http://people.physics.anu.edu.au/~amh110/turbo_engine_ouputs.htm

If I had to guess the different boost pressure was probably due to different gasoline mixes and stricter US emissions relative to Europe. This was the early days of turbocharging on a mass produced car so I bet that they were being cautious (I don't count stuff like the Corvair Spyder and Oldsmobile Jetfire because those had carburetors and were prone to detonation if owners weren't attentive).

You can probably rectify the difference with a manual boost controller and/or intercooler should you so desire.
 
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There are several differences. Plus the conservative attitude of Volvo meant that emissions had to be more strict. So, besides the lambda control for fuel mixture. The B21FT also used the lambda control for fuel enrichment under boost. There is a boost enrichment switch on the firewall which raises the dwell cycle on the controller to provide more fuel above about 2.9psi.

So, the B21FT uses electronics for more fuel while the ET engine uses the boost pressure on the control pressure regulator to provide enrichment under boost. No cat converter does mean a bit more flow as well. The fuel injectors in the ET are the gold ones which from what I have learned have a different opening pressure and have a finer spray pattern than the injectors used with the B21FT. So, the injectors and control pressure enrichment is probably where the extra power is from. :cool:
 
I had no idea that there were so many differences! Thanks for your help.

Is there some easy way to increase the power without an IC? Maybe increase the boost to one or two more psi? The car feels really tired and I'm kind of dissapointed. I had hoped for a more alert car. Maybe all the US Turbos are like this? It may also be that the catalytic converter is clogged and makes the engine more tired. I'm going the check that.
 
When I bought my turbo the converter was clogged. It's very common on the US models. The converter is very close to the engine and gets a lot of carbon from the exhaust building up inside. On the US models without intercooler you can raise the boost to about 8psi. But I would just get an NPR intercooler and then you can raise the boost to 11-12psi and actually have some fun.
 
When I bought my turbo the converter was clogged. It's very common on the US models.

Yes, agreed. Since the poster is in Sweden, he can still probably source a B21ET downpipe (with no cat installed).

But I would just get an NPR intercooler and then you can raise the boost to 11-12psi and actually have some fun.

Or, just get one of the do88 all metal 240 intercoolers. Probably cheaper to source one of those in the Motherland vs. the NPR.
 
Yeah, there's still about 40 original downpipes in stock at GCP/Volvo. I thought about buying one but I want to test first if the converter is clogged or not. There's a plug on the side of the converter. If I remove the plug it will probably make some difference in the exhaust flow. But I don't know if I want a B21ET downpipe. It's quite nice with a converter considering the smell and the enviromental benefits. However, that all depends on how much in differs in the power output haha.

I would prefer to have an original intercooler kit installed, but they are really difficult to find. Is it possible to install just an intercooler and nothing else? Will the engine still run well and have increased power? On the original intercooler kits I belive there were a sensor or something like that and some kind of valve.
 
You don't need the timer/solenoid for the intercooler install. Just run a manual boost controller to add additional boost pressure. That is all the timer/solenoid does.
 
You don't need the timer/solenoid for the intercooler install. Just run a manual boost controller to add additional boost pressure. That is all the timer/solenoid does.

Do you know if there's a guide on how to install an aftermarket intercooler with a manual boost controller?

I just found an original almost complete intercooler kit on a swedish counterpart to ebay. However the seller wants at least $700. It would be nice to have an original IC kit, but I don't know if its worth that much money.
 
For that much money, I would buy this intercooler (https://www.do88.se/en/artiklar/volvo-200_700_900-turbo-81-98-intercooler.html) and some hoses.

For diagram, I believe this is the B21FT intercooled one
GR-34929.jpg


On a related note, I've always thought the power difference was also attributed to the octane of the gas in Europe vs US; I thought the former was higher.
 
If I buy the Do88 intercooler, how do I do with the mountings? I've understood that the original IC-mountings are hard to find, the ones that are both for the radiator and the IC. If the IC on the auction site was 100% complete and in its originial box, then it would be worth the money according to me. But now a hose, a relay, a cable and the box is missing. It's only the intercooler, hoses, mountings and the solenoid.

That may be true. Or maybe it was back in the '80s. In Sweden we normally use 95 octane gasoline. 98 octane is available as well. I don't know how it is in the US.
 
Here in the states, octane ratings are calculated differently. (R+M)/2=the octane number at the pump. 87 octane is 91 RON. 92 octane is around 98 RON. R=RON or Research Octane Number, M=MON or Motor Octane Number.

Re: the intercooler bracketry, the upper rubbers are the same as the 740/760 parts. Lower rubbers are the 740/760 parts, minus the tab that hooks onto the 700 series radiator core support, and usually with a rubber nipple that goes into the holes of the radiator crossmember of a 240. You can cut the tabs off, then lay the lower rubber mounts into the 240's crossmember slots. The metal bracket, if someone can get measurements, you can probably have a machine shop fabricate some up for you.
 
Thank you John! I'll get my hand on 740/760 brackets then. I guess they are easier to find than the original 240 brackets. Which one is the metal bracket you mentioned? How about the fan cowling? Is it also the same as the 740/760 fan cowling?

I think it's a much better idea to get aftermarket intercooler parts. Since my 245 Turbo isn't going to be 100% original it's not really worth hunting down and paying way too much for original parts.
 
How about the fan cowling? Is it also the same as the 740/760 fan cowling?

I would think so. With that said, maybe the cowling in your 240 will suffice? If you want, I can take some pictures later on today of mine and do some measuring

I think it's a much better idea to get aftermarket intercooler parts. Since my 245 Turbo isn't going to be 100% original it's not really worth hunting down and paying way too much for original parts.

Also, the original Volvo intercooler is nothing to be proud of
 
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For the upper bracket to hold the intercooler you can use the upper 740 brackets. You just have to slot the bolt holes so the bolts will work. The fan shroud is too long to work. You can try to cut down the plastic fan shroud or find a 240 intercooled one. I think Volvo may still sell them. If you put a listing in wanted. Someone here will sell you the fan shroud you need.
 
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Yes. Our US cars have the T cam. I don't know if this is correct or not. I was told the B21 ET came with a bigger turbo. I know the German market Turbo wagon that RSI ended up with had a bigger Turbo on it than the US market cars came with. Whether it had been upgraded at some point is unknown.
 
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