Vortech
Supercharged 4.6L Mustang GT |
Vortech
Supercharged 4.6L Mustang GT |
| Last
year, my 1996 SOHC Mustang GT ran a best pass of 11.27
seconds at 127.3 mph and made 500 hp and 493 ft-lbs as
documented in a previous Corral article. Link to previous
article: Some changes were made before starting this season due to a catastrophic engine failure during a dyno test session at the end of last year. It turned out to be an assembly error on my part as I had apparently not installed one of the piston pin clips properly and it came loose. Lesson here: Always double or triple check your work, especially if it is some critical component that is hard to access at a later date. Engine: Managing to find a new stock 1998 engine for a decent price, I bought it. Since the SVO heads and intake manifold would be getting installed, I removed everything down to the shortblock. All of the SVO stuff from last year was installed along with a 2.5" Vortech pulley (instead of the 2.625" pulley last year). The SVO heads received a slight cleanup in the port bowl area just to remove any edges. But another problem appeared with the heads. Apparently, disassembling the engine so many times and swapping cams (the ones I was using were not new either) caused a problem with the front cam bearing area on the driver's side head. I should point out that calling it a bearing is somewhat misleading since there is no real bearing insert, the cam just rides against the machined cam bores in the head. The camshaft journal seemed like it would be okay with just a simple cleanup with some polishing paper. The head had some deep scrapes though and I was nervous about reinstalling the cam since the front bearing gets a lot of loading on it from the timing chain pulling down. But the solution was quite simple since the heads are reversible - meaning the left and right heads can be swapped for each other as long as the oil galley plugs get installed in the correct locations. The bad bearing would now be in the rear of the passenger's side head where there is no load on it at all. However, installing the cam in this head showed that it was scraping on the head bearing surface. So, since it was already damaged, I decided to really take care of it by grinding the bearing surface in the head larger so that it wouldn't touch the cam at all. But this posed another problem because the cam bearings get oil fed to them by drilled holes in the head, so I tapped the hole to this journal and plugged it. The heads were installed using stock head gaskets and head bolts. The following picture shows the combustion chambers of the SVO heads (although not too clearly). The "bowl" is the shiny area between the valve seats and the valve guides. The bowls show up shiny in the picture (especially on the exhaust) due to just getting cleaned up with a die grinder. I always lap the valves with grinding compound whenever the heads are disassembled; in order to make sure there is a good seal between the valves and the seats. The valve seats are a rusty color, due to the lapping and that the heads were just washed and rust was already starting to form. In fact, the water spots are still visible in the picture. |
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| The
following picture shows the rear cam bearing area of the
passenger's side head. Note that the oil galley plugs
were not installed yet after swapping the heads left and
right and cleaning them up. Make sure you always install
the plugs, otherwise you will have a massive oil leak and
it is very difficult to install the rear plugs after the
engine is installed in the car.
Also, since the car does not use A/C, I decided to simplify the FEAD (Front End Accessory Drive - pulleys and belt) by removing the A/C idler bracket/pulley and the stock tensioner and rerouting the belt. The belt tension would now be adjusted by the alternator, as a slot was cut in the alternator mounting ears so it could be manually repositioned to change the tension. This slot is similar to what the DOHC (and some newer SOHC) alternators have, but they are on those alternators for installation ease rather than belt tension adjustment. The following picture shows a newer stock alternator with the slots and the alternator I was using prior to cutting the slot (on the right ear in this picture, which would be the driver's side in the vehicle). You can also see the large pulley being used on the alternator. The alternator I am using is a 95 amp unit instead of the normal 130 amp because I don’t need the extra current capacity and the smaller alternator has less rotating inertia aside from being a little lighter.
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| The
following picture shows the FEAD belt routing used. The
belt tension is adjusted by loosening the alternator
mounting bolts and just tilting the driver's side upward.
Obviously there is not much adjustment range, so a very
tight fitting belt had to be found in order to use this
method.
List of non-stock engine/power related hardware (so you won't have to look at the previous article):
Suspension/chassis: A desire to do some autocrossing/roadracing meant some other changes were needed in order to stiffen up the suspension. So the following parts were purchased from Diversified Products Marketing and installed:
New Monroe quadshocks were installed because a stock one started leaking at the end of last season. Also, the stock swaybars were reinstalled along with the T-5 trans and safety bellhousing from last season. Since my old favorite, Detroit Dragway, permanently closed this year, testing had to be done at another Detroit area track. Going to Milan Dragway on 7/9/98, ran a best pass of: 13.297 seconds at 98.00 mph with a 2.025 seconds 60 ft time Well, everything was fine until after tech inspection at the track when the car just decided to not start. I had leaned out the cranking fuel by mistake just like last year when it did the same thing, so I recalibrated it quickly and it started okay. 1st pass had lots of smoke that was mostly fuel I think from what had been dumped into the exhaust while cranking it over without starting and maybe some residual oil from the rebuild. I was just getting a feel for the car again so I took it easy and only ran 13.3 at 109 mph. 2nd pass had no real smoke, but the car felt like it was way down on power just after about 1/4 track. Found I had no power steering to take the turn at the end of the track (surprise!) and then noticed the alternator not charging. Driving slowly back to the pits and then opening the hood revealed that the belt had shredded. The engine got rather hot too since it had no coolant flow for most of the ¼ mile pass. We had another belt so we changed it and started the engine, but now it ran rough. Pulled injector connectors one at a time and found #5 cylinder doing nothing. Removed that sparkplug and found something had hit the electrode and closed the gap. Deciding to risk it, we just opened up the gap and tried starting again and the engine ran smoothly. However, blipping the throttle resulted in a very strange sound. Sort of like a scraping combined with an odd knock. Not knowing what that was, nor feeling like tearing into the engine at the track, we put it back on the trailer and headed home. Not really a good time at the track, nor was it a good way to start off the new season. Some additional vehicle modifications were made at this point: An SVO Cobra R radiator (part number M-8005-R58) was installed for improved cooling for the planned autocrossing/roadracing. This is a very large radiator and is not a simple bolt-in. New brackets must be fabricated to support the radiator. But since it is thicker than the stock one, it really interferes with the Vortech inlet tube, so a different mounting approach was taken. I decided to cut the bottom of the front crossmember under the stock radiator and reweld it in a lower position so that the radiator could be moved forward. New support brackets for it and the stock cooling fan were fabricated and attached. The coolant reservoir no longer fit well, so a spare power steering reservoir was chosen for that task and was mounted on the inner fender where the battery used to be. Spending a while at a local autoparts store looking at radiator hoses paid off, as some hoses were found to match up to the smaller diameter fittings on the new radiator. The following picture shows how far forward the radiator was mounted. A word of caution for anyone planning to do something similar - I've noticed some Cobra R radiators (with the same SVO part number) have the filler neck in a different position and may require more work to locate the radiator this far forward.
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| One
thing that really annoys me when working on the 4.6L when
it is still in the engine compartment is the routing of
the hydraboost lines to and from the power steering pump,
the brake booster and cooler. I decided to reroute these
lines between the inner and outer fender on the driver's
side. It took a bit of fabrication, but really gets them
out of the way when doing engine work. It was also a good time to do some relocating of wiring to clean up the engine compartment. The underhood fuse box was relocated between the inner and outer fender on the driver's side. It is still somewhat accessible if needed, but I'd never blown a fuse in it yet so I wasn't too worried. With the hydraboost lines and fuse box relocated, the engine compartment looked much less cluttered. The following picture shows how much more room is now available to work on the engine while it is in the car.
To firm up the rear suspension, BBK rear control arms from Summit were installed. They appear to be very stout pieces and have grease fittings to help combat the annoying squeaks that seem to be common with urethane bushings. The top bushings in the axle were left stock so as not to cause excessive binding. Finally deciding to not do anything with the engine other than run it more to see how it was doing rather than tearing into it right away, it was left alone except the Vortech was removed just to be safe. Plus I had been wanting to try the car at the track naturally aspirated, so a stock Cobra airfilter/meter/hose assembly was installed. Going to Milan Dragway on 8/7/98, ran a best pass of: 13.532 seconds at 104.57 mph with a 2.136 seconds 60 ft time Not very good at all for what was in the engine. However, the weather was very hot and humid and I had not made calibration changes to optimize for running without the blower (other than changing the air meter curve in the EPEC). To make matters worse, the car got a flat tire. This season is not going well so far. The following (poorly lit) picture shows the "short belt" arrangement used without the Vortech in place. The belt just wraps around the crank, water pump, alternator and power steering pump pulleys. This works very well using the alternator modifications already mentioned as the belt tensioning method.
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| More
changes for durability and more power potential: Since they are Mustang racers becoming even more noted for their drivetrain business and I had bought from them in the past, I once again contacted D&D Performance. After discussing how I planned to use the car for dragracing and autocrossing/roadracing, we settled on what would be the best components for me to buy. Using the stock axle housing, D&D fitted the following parts:
After it was all completed, Mobil 1 synthetic gear lube was poured in. It should also be noted that the stock axle shafts removed from the car looked to be in great shape even after having lots of dragstrip passes with sticky tires and considerably more than stock power. It does show that the stock parts appear to be very robust, at least when not using slicks. Discussing the transmission requirements with D&D, we settled on the following components:
Since the safety bellhousing was meant for a 5.0L application, some modifications were necessary to make it bolt up to the 4.6L engine. I had done this mod before and written a tech article so I won't go into detail here. Besides, safety bellhousings that fit the 4.6L are now available, so there should be no reason to go through this effort anymore. Link to bellhousing modification article: http://www2.corral.net/modular/tech/bell1.htm D&D also recommended using GM Syncromesh transmission fluid and to not shift the trans hard until after a break-in period if I wanted it to shift smoothly later on in its life. In order to help me comply with that last suggestion, I decided to leave the stock Tremec shifter in place as a reminder to take it easy on the trans for a while. |
