View Full Version : Working on my "new" engine...

08-10-2008, 02:29 AM
Been a while - I have been busy at work and life has been in the way of posting here! Will read up on the threads after I post this.

Anyway I needed an engine block and found a complete (down to the ECM, sensors, accessories, and wiring harness) 3.8 SFI engine for $100. Only problem was a thrown timing chain and bent valves. This is a factory roller-cam engine and has a very stout block that weighs many pounds more than my 3.0 block.

The only logical choice was to rebuild this engine and retire the 3.0 draw-through turbo engine for some other project.

I carefully unhooked everything at the salvage yard, kept all the parts and hardware and had the yard crew pull the engine and put it in my truck. This was a deal indeed!!

The 87 3.8SFI, stock puts out 165 HP, no turbo, plain-jain stock. The 1979 3.8 turbo (what I was building originally) put out 180 HP stock. This engine is almost as strong with no turbo than the older one was, with boost!

So I have been planning an all-out off the deep end 3.8 SFI Turbo from Hell. My goal is to lay down at least one dynamometer pull at or above 500 HP. If I can get the transmission to hold it. Everyone who "knows" Buick engines says this is an "easy" goal and I should shoot for more. But the transmission will be the limiting factor.

The 1987 3.8 SFI FWD engine is equivalent to the Grand National engine "109" casting engine block (the super badass ones, in other words) plus it already has the roller camshaft lifter guide mount points in the block.

Just did some work it, getting the heads and manifold ported and the timing gear system worked out.

There is a high performance turbo camshaft for this engine since it is a direct decendant of the mighty Grand National 3.8. The only problem is, the GN was rear wheel drive and had a gear-driven oilpump and ignition timer device. The camshaft for it is the same as the old carburetor 3.8. It has a mechanical fuel pump lobe, and an oilpump / distributor drive gear.

My engine is a Front Wheel Drive engine from 1987. This had a factory installed roller lifter camshaft. The block is equipped for the retaining hardware for the roller lifters. The cam has no provisions of a mechanical fuel pump and has no distributor / oilpump drive gear. Therefore the camshaft is shorter. To use the readily-available RWD Grand National high performance camshaft in my FWD engine, I had to have the front end of the cam machined to match the engine's original camshaft.

This turned out excellent! Instead of the gear-driven ignition timer device on the RWD engine, my engine has a separate cam position sensor and crank trigger. Instead of a gear driven oilpump, it has a gerotor-type oilpump that is direct-drive off the lower crankshaft sprocket. It turns at crankshaft speed and is a much better systen than the old gear pump. The front of the engine is more compact and the oil filter bypass issue is reduced. But the aftermarket Grand National camshaft had to be modified!

Engine as-received:

Engine during rebuild. Pictures are annotated:

Okay - some trivia! There are 2 versions of this ignition system. One has a single crank trigger ring, and the other has two crank trigger rings with differing numbers of slots. These rings are on the back of the harmonic balancer.

My engine has the single ring system. It has a metal cam trigger magnet that is not able to break off the cam. This is a good thing because this system depends on the cam sensor to operate the ignition. If the cam sensor or the magnet fails; the engine can not run. The pictures above, of the old "3.8 SFI" engine are the old style where the cam signal MUST work for the engine to run.

The newer ones with the dual crank trigger ring use the cam sensor only for timing the fuel injection. The engine will run with or without it. These have a cheezy plastic cam trigger magnet that is famous for breaking away and causing the Check Engine light to come on. The picture below shows the "newer" system used on 1989 and newer "3800 SFI" engines.

The newer ones start with less cranking because the dual crank trigger gets synchronized within 2/3 of a crankshaft rotation. After 2/3 of a rotation, the ignition system begins firing sparks and the engine can start.

The older ones (like my engine above) require up to TWO crankshaft revolutions before the cam trigger has given the ignition sync signal it needs to start firing sparks. So the starter has to turn over longer before it cranks up.

New-style cam magnet (needed only for fuel timing, engine can run without):

85 Holiday
08-10-2008, 04:06 AM
Where did you get 165hp? Everything I have seen about the 3.8 in my ciera which looks like that one rates it at 150hp 200tq. 165hp started with the VinC 3800

08-10-2008, 05:40 AM
turbo your looking to do 500hp. did you look in to the superchaged veriosn i think they has oil sqerters on the the under side of the pistion

08-10-2008, 02:16 PM
Holiday; I don't remember where I got that HP rating. I beleive it was from the repair manual. I see it is listed as 150 HP elsewhere online. There are so many different versions of this engine. As with many OEM

Durock; I wish it had piston oilers but none of the old 3.8's do. It is the same internally as the Turbo Regals and they were rated 275 HP. Their enthusiasts make 500 HP routinely without piston oilers.

In a car, it is hard to keep a high HP engine "full-on" more than a few moments. Normally before the pistons overheat either the tires burn off the rims, you finish your pass at the drag strip, or the car reaches a dangerous speed and any sane individual will slow down.

If it was going to be a continuous-duty high HP engine then it would definately need oilers! If this were a truck motor or a stationary engine (generator, pump, etc) it would need to have a continuous rating astablished. This is done on an engine dynamometer while monitoring exhaust temp, oil temp, charge air temp and other operating conditions. As a GUESS I would say with proper cooling system and intercooler you could run this engine at 200 HP all day long.

This one is just a toy - it will be driven on the road under 15 to 30 HP loads - with 5 and 10 second blasts of insanity now and then! :kekeke:

08-10-2008, 06:30 PM
With PASSENGER CAR engines, many factors go into the engine's "published HP rating." The same engine can have different ratings from year to year as the ECM calibration is updated and adapted to encompass new pollution and fuel economy standards. Sometimes the manufacturer will give a lower rating than the engine can actually produce, to allow another (usually more expensive) model of car to have "the most HP."

With industrial engines (this is my background) the HP rating is given, along with the operating conditions that must be met for this rating to be safe and effective. The engine is guaranteed (as in legally guaranteed by warranty) to produce this HP or better.

If this 3.8 had a factory rating of 150 or 165 HP it is applicable with the original ECM settings which are a compromise at best.

The cam in this engine opens the valves more rapidly and opens them further to reduce air restriction at the intake and exhaust ports. By its self this would give the engine more power. How much? The cam manufacturer wants you to believe it adds 15 HP to a normally aspirated engine (no turbo).

The ports and manifold runners are mass-produced and they are a compromise between ease of manufacture and airflow. By smoothing out the path of air by "porting" the heads, this further reduces air restriction internal to the engine.

When I rebuilt my mom's 3800 (Vin C) I ported the heads and manifolds. The engine is making 190 HP based on the calculated airflow at the MAF meter. From the seat of the pants, it feels like it has every bit of that.

With a turbocharged engine, the turbo will push the engine to whatever level you take it until something breaks or the system reaches equilibrium.

By limiting air restrictions in the engine, it will reduce the amount of boost pressure the turbocharger has to produce to allow the engine to reach its HP goal. It is easier for the turbo to blow 500 HP worth of air through a smooth port with a fully open valve than it is to push it through a rough port with a half-open valve. The result is less heat in the air because the turbo is not working as hard.

The limiting factor on a turbocharged engine is detonation. The hotter the air when it enters the cylinder the less boost and less timing advance you can have, therefore limiting power. Anything you do that cools the air charge, or reduces the amount of boost needed to reach the HP goals will take stress off the engine and raise the potential HP level before detonation happens.

Sorry to get into all this theory but it may interest someone! It boils down to this - the factory rating is irrelevant once the engine has been modified.

The ECM I plan to use is the same Delco 1226869 ECM that my T-Type has. It is speed-density and has no airflow meter. This further reduces airflow restrictions. With a 3-bar MAP sensor, the system can respond to boost pressures up to 30 PSI, without going outside of the VE or spark tables in the ECM.

85 Holiday
08-11-2008, 03:24 AM
No problem, I am sticking with 150hp 200tq. That motor has no where near the power of the 2 L27s I have.

09-16-2008, 02:31 AM
See this thread. (http://www.a-body.net/forums/showthread.php?t=1225)