Re: 240 GLT (RearWheelPaul)
Hopefully we can keep this discussion going.
| Quote, originally posted by RearWheelPaul » |
| The turbo motors are fitted with forged crankshafts (to prevent crank whip or breakage during high boost conditions) |
I have never seen any positive proof of this being true. Seems to be an old myth. I've heard of B234F engines having a forged crank (Dick Prince in Australia claimed to pull a forged crank from a B234F), but many people have cracked those open to find a cast crank here in the states. Please show me a forged 80mm stroke B230 style crank that comes from a car engine, particularly a B230F/B230FT. They're cast. The 86mm stroke B230 crank from Penta engines is forged. I have a side by side photo if anyone is interested in how to tell them apart. But no one is breaking cranks. The way the rod, piston, and crank fit together may be of more concern than the material and method of manufacture of the crank.
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| sodium-filled exhaust valves (to prevent a burnt or dropped valve) |
I'll give you that one. Something my turbo engine will have. But that's not to say a solid valve can't handle the heat in a relatively low output engine. Philip Bradley had troubles with his big valve head due to excess heat, but I believe that was down to valve material AND undersized stock valve seats that were ground to fit the larger valves. On another note, a friend of mine had a machine shop inspect the sodium filled valves, and found the stellite coating to be VERY thin. I'm not sure that grinding the turbo valves makes much difference either way.
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| different heads (to improve off-boost port velocities and maintain an acceptably low compression ratio) |
Same casting, turbo or non-turbo. What are the differences between a 530 on a B230F and a 530 on a B230FT, besides the exhaust valves & cam?
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| different camshafts (to prevent overheating the exhaust valves and turbine stage while enhancing off-boost torque), higher flow fuel pumps and injectors, to name a few. |
I don't believe the cam will affect long term durability, but I have no info to support that either way. The M cam actually has less overlap than the T, so it will provide similar driving characteristics (poor, in my opinion). There are a number of performance turbo cams that won't kill the top end power like the T cam. Fuel pumps...a good thing to upgrade just based on the age of the cars, even if increased output is not desired. And of course the injectors are larger. But I thought this was about a 240 GLT turbo car? It's already prepared for the turbo, so it just needs a short block...
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| While the many respondents didn't see any problem with backyard turbo mods, there were others who privately e-mailed me thier little tales of mechanical horror in which frequent breakdown and high cost were persistent themes. |
Mechanical horror is still very common. It comes from those who push the limits, or don't know the limits, or don't prepare the car properly to handle what they throw at it. Adding a turbo to a non-turbo engine is something relatively new in the world of RWD Volvos, and those who chose to do it generally have the means to build it themselves, and repair it if it breaks. We seek more power, so yes, parts will break, and rods will exit the block on occasion. Personally, I have only one car to drive, and I'm not likely to be patient with boost. I know I will want more, therefore I have chosen not to turbocharge my '87 240 with its weak B230F. If I had a second car, I'd turbo it ASAP.
I'm trying to dispell the myths that this type of thing can't be done. It can. It does have some risk associated, but there is an upside as well. That is increased torque and increased response from the engine without spending a large amount of money.
A friend of mine has a '88 245 DL with the weak 9mm rod B230F engine, running a T25 from a '91 940SE at close to 15lbs of boost. Completely stock, untouched bottom end with probably 140k on it. Now because he's running programmable fuel and ignition control, I don't think he'll grenade the motor from lack of fuel or from detonation. Therefore, I don't know what would make the engine expire if it doesn't detonate and crack a piston and/or bend/break a rod. The car is a monster, and with the high CR and tiny turbo, it makes unbelievable torque at very low rpm. It still uses the M cam, an unmodified '90+ manifold, a 740Turbo downpipe, and the standard 240 exhaust.
I've witnessed about a dozen similar cars, running B230F bottom ends and 7-15+ lbs of boost. Some use the LH2.2 or LH2.4 turbo fuel and ignition computers, plus stock turbo injectors. Some are using Megasquirt. For the most part, it's a reliable setup if done prudently.
With all due respect, I don't think you have any idea just how many people are doing this now. 5 years ago when I was reading the brickboard and someone asked about adding a turbo, it got the same response you just gave. But in recent years, more people have given it a shot, more volvo turbos are ending up in junkyards, parts are getting cheaper, and it's become rather common to +T a non-turbo engine.
If you use a B230F L block, you get piston oil squirters too, which increase the detonation threshold.
If you want to do it right and spend a lot of money, rebuild an engine to around 9:1 CR, deck the block for tight squish, deshroud the valves, port the head, buy a performance turbo cam, get a '90+ manifold and a nice turbo, and go to town. Some of these galleries have excellent information about rebuilding a B230. He doesn't seem to list compression ratio, but I know at least one of the tight squish engines he built was running in the neighborhood of 10psi on 87 octane. The fast burn characteristics allow the lower octane with no ping.
http://www.pbase.com/stealthfti
I'm doing a B23ET, about 9.3-9.5:1, with extensive combustion chamber and port work, swirl polished stock valves, ported '90+, 60/63 T3, V cam, and probably Megasquirt after doing some initial running on LH2.2 Turbo. The T3 should be happy around 18lbs of boost and should make very nice, very responsive power. My project started when I bought a set of B23ET pistons, new with rings, for $112 shipped to my door. Had I not found that deal, I'd probably be using a B230F L block from my local junkyard for $150, and it would alredy be up and running. Engine builds are expensive. Mine isn't, but it's taking forever.
Do what you want. If you have to pay someone else to change an engine, maybe a non-turbo block is too risky for you. If you don't know how to get more fuel from k-jet, maybe higher boost isn't a good idea. But I sat in the passengers seat of my friends 242 Turbo intercooler on the dyno while it was tweaked to put down about 220lb-ft of torque to the wheels at 14psi using the factory k-jet on a B21FT engine. A B230F would make that torque at lower rpm with less boost.
My 2 cents, as a non-turbo driver, from the Turbobricks side.
