B21ET 250/300 HK ( Engelsk text )

[Danne Engberg]

Det här är Ivars text som har legat på turbobricks sedan slutet av 90-talet


This article explains how to build up a B21FT/ET engine with an eye towards low cost.
If your engine is nearing overhaul time and you are ready to spend some (but not gobs of) money for some serious power, this might be the engine performance recipe for you. The approach is based on the real life experience of a capable Norwegian tuner named Ivar Finnvik.

Now this is not the be-all and end-all of 240 engine buildups. However, it has a lot to offer. This is what Ivar says about it:

``Don't misunderstand me, a really well built engine with many special parts and a real programmable injection and ignition system will perform much better but this but this isn't hi-tech tuning, as high tech tuning usually also means hi-cost. This gives a powerful and reliable engine for relatively little money. Take the rest of your savings and use it on the suspension and steering.You will need it!''.
What are the pros and cons?

Pros:

The pros are few but pretty convincing:

250-280 hp with 36-37 Kmp (255 ft./lbs) of torque (more if you apply the RMOs)
guaranteed ego deflater for other red light racers
Cons:
The cons are far more numerous however, if you can live with them, this engine performance recipe for you:

A 3000-7000 rpm engine - the low end is weak but this IS the price to pay for this low cost buildup
Uncontrolled emissions
High fuel consumption (15 L/100) or around 16.5 US mpg, with a light right foot according to Ivar!
Potential spark plug fouling - unless you drive hard with ensuing effect on fuel consumption
Needs 98 octane fuel or equivalent (use a good octane booster).
Does not work well with a LAMBDA setup.
Ivar's approach is to build an engine that gets much of its cooling from a rich fuel charge during high boost. Since Ivar is talking 17.5 to 20 psi boost, an 8 port fuel distributor and high-flow injectors are essential components. It is somewhat primitive but it works without a knock sensor system.

Unfortunately, if you live in an area where smog testing is mandatory, this relatively rich-running engine buildup is not for you.

On the other hand, this seems a good recipe for anyone who plans to race a turbo at club events.

You can also build on/improve Ivar's basic recipe (as your wallet allows) by checking out the associated Rich Man Options (RMOs) included along with Ivar's recipe. These RMOs will raise the cost but are likely to send you into the 300+ hp range and make your car more streetable.

Is this approach a waste of time and money?
If you don't mind a one-shot infusion of heavy cash into a B21FT/ET (using custom pistons, rods, metal hardening processes, etc.) to get a 450 h.p. engine, Ivar Finnvik's recipe is not the ideal path to follow even though many of the recommended parts can also be used in a cost-no-object buildup. If you follow this approach and then want to go all-out, you are likely to need a full teardown at a later date.

An advantage to Ivar's method is that you can later add the RMOs for more power. This means that expenses can be spread over a period of time and the end results should get you well above 300 hp.

It is a matter of personal finances, time, and in the end, final objective. A last word of caution, this is an engine buildup only - your stock transmission and clutch are in for a real shock - be prepared to do something about it.

The job
You don't have to do a complete engine rebuild but frankly, it makes sense to do so. Complete rebuilding instructions are not within the scope of this article but proper professional overhaul practices are highly recommended. What you will find in this article are all the important and essential steps to Ivar Finnvik's engine performance recipe along with some RMO options. Get out your tools and let's get started:

Take the B21FT/ET engine apart and remove the pistons.
Machine 1 mm from the piston tops and reuse them in the rebuild. Your static compression ratio will now be about 7.0 to 1.
The compression is lowered since this engine will be running high boost which is better handled with this lower static compression ratio. There will be less torque at low rpm but the recommended Group A turbo (or equivalent) destroys the low end anyway. The real power band of this engine is 3000-7000 rpm.
Install new piston rings and bearings (assuming decent bores).
Inspect the cylinder head for cracks and other faults. If it checks out OK, use an appropriate grinder (such as a Dremel tool or high speed rotary file) to round off all sharp edges in the combustion chamber. You can also unshroud the inlet valve area, and optionally the exhaust area, but make sure all combustion chambers are the same size (CC them).
If you like grinding, take your skills to the cylinder head ports. Don't remove more than 1 mm all around. Start with the exhaust port side, since this is the best payoff in terms of power per work hour spent doing this kind of work. Once you are happy with the exhaust, go to the intake side.
If you don't like grinding, Ivar suggests that you use a 405 or 531 cylinder head. He claims that they flow better in stock form than other mildly ported heads. Just grind out the exhaust side a little on these heads.
Check the exhaust manifold for any faults or cracks and if required, weld it with stainless TIG.
RMO #1: install a '90 or later exhaust manifold.
Buy a gasket set from Elring. This is the best set with the strongest head gasket and the best exhaust outlet gaskets. These gaskets can normally handle 250-260 HP without o-rings. If you cant get Elring, buy Genuine Volvo, it's Elring!.
RMO#2: If you want more than 260 hp, have the block O-ringed.
Use new head bolts but of the older style with 10 mm Allen (female hex) heads and give them a little more torque than recommended. The stock recommended torque is 110Nm (??? ft.lbs). These bolts can easily handle an extra 20 Nm.
The stock turbo isn't the best choice, but can be used up to about 1,1 bar (16 psi).
Use your savings and buy an exchange turbo with Gr A specifications with a wastegate set to 1,2 bar. [17.5 psi]. In the US, that means a T3/T4 hybrid or the 60-trim T3 (good for 300+HP).
Take out your intercooler and make a framework around it so that the plastic ends can't get blown off.
Visit a junkyard and locate a V-8 fuel distributor from a Porsche 928 or a Mercedes V8 (450 or 500 models). Also get either an ``A'' cam (B21A carb engine) or a ``K'' cam (B23E w/o cat).
If you live where these cams are unavailable (USA), contact turbobrick member Denis L'Esperance for arrangements on getting one from Canada.
Install the cam and adjust it with 3-5 degrees of advance.
You can buy a special pulley or make an offset cam locating pin.
Adjust the valve clearance to 0,45-0,50 mm (0.018 -0.020'').
Make a new housing for the fuel distributor from fiberglass and connect a K&N filter to the top of the inlet on the top of the distributor.
Go to a Bosch dealer and find some high flow injectors (capable of delivering about 300-350 ml/min.).
We are aiming for 350 ml/min injectors to guarantee a flow of about 280-290 ml at 20 psi boost (1.4 bar) with the V8 CIS fuel distributor.
Connect two fuel distributor outlets together whose combined output goes to one high flow injector.
Take out the system pressure regulator valve from the distributor and use an M5 washer as an extra shim on the spring. The system pressure should be about 6 bars (88 psi) now.
Install colder spark plugs like NGK BP8ES.
Note: this is a cold plug - great for racing but quite susceptible to fouling in traffic, you might want to try an NGK BP7ES or go with the following RMO.
RMO#3: get an aftermarket ignition system or at least a high voltage coil.
Renew the fuel filter and any other filter.
You may need to buy a high volume main fuel pump to the feed the engine, but normally the stock pump in good condition should manage.
Make sure you have a good clutch and transmission.
RMO #4: get a Getrag 5 speed.
Install a 2.5 inch or 3.0 inch exhaust system (bigger is better here).
Set the static ignition timing to about 5 deg BTDC.
This is low but without a boost and/or ignition management system, you need the retarded setting as a weapon against detonation. The stock distributor is also a limiting factor and must be set this retarded to operate well at high power limits.
RMO#5: install John Bertram's APC system. Install an aftermarket ignition system that will allow you to use higher than stock static advance (check out the MSD 6 BTM) to regain the sorely missed (in traffic) low end torque.
Testing and adjusting the engine
Start the rebuilt engine and take the car for a test drive. At normal working temperature, use a CO meter and adjust the control pressure until you get an idle CO content of about 3-4%
To adjust the control pressure, you can use one of two ways:
open the control pressure valve and bend the bimetal plate. Not the best way, but it works.
a better way is to drill a hole (approx. 6 mm) in the thin metal cap on the underside of the control pressure regulator. This exposes an Allen (female hex) head screw. Turn it up or down to adjust your Control Pressure.

Set the control pressure to about 3,0-3,2 bar [43.5-46.5 psi] at idle with the vacuum hose disconnected.
Set the turbocharger wastegate to 1,4 bar, [20.5 psi].
Take a test drive and try to get the engine running as smooth as possible adjusting control and system pressure. Listen carefully for detonations and correct this with more fuel.
Buying the parts
You can find a number of parts from Stefannsson Automotive (SAM):

Gold injectors # 95082322 SEK 842 ea
Fiberglass air inlet # 95082324, SEK 12,85
Exhaust manifold 90 era # 95082549, SEK 3,288
K&N filter # 95082351, SEK 578
The Getrag M51 is an expensive option but should eventually be considered.
The Porsche 928 and Mercedes V-8 fuel distributors cost about $450 and $250 respectively and are easily found in any well-stocked junkyard. Get one from a 1984 -85 Mercedes 500 if you want to try to get this all working with a lambda system (this fuel distributor has a frequency valve). Actual price depends on your location and parts availability.