Looking at the picture of your block at your website, and seeing how out of the five main caps, Mitsubishi ties the two outer sets at either end together to add rigidity, and now on the current version of that identical motor, they tie all five together should tell you something. They couldnt possibly be having any issues with bottom end rigidity? Right? I'm sure that your motor runs fine, I am not arguing that with you, I do not know what the setup is you have. But this is the way that I do engines. Instead of if it aint broke mentality, I attempt to solve the problem before it has a chance to occur.

What we have here is a difference in philosophy.

 

I think I can safely say I have built more 4g63 engines than quite possibly anyone else in this country. I am quite sure we are nearing the 1,000 engine mark, this is no joke.

We have been building the 4g63's for nearly 15 years now. This has been our main focus all of that time.

As most of you know we were the first to crack just about every barrier there is. We were the first to crack the 12, 11 and 10 second barriers in an AWD DSM. The first 4g63 powered DSM to crack the 9, 8 and 7 second barriers too. Needless to say I don't think anyone can argue that we have done some homework.

The statement that the 4g63 block isn't good for high horsepower without major machining is quite frankly complete bull****. Now the fact of the matter is that the machine work that IS required when building one HAS TO BE done correctly or you will be screwed.

The major lightening of the crank that I see here not only is a waste of time in my opinion but will cause problems in the long run. There are quite a few guys that have tried this already and have nothing but problems. Polishing of the inside of the block is another area that just isn't needed. Yes, like a rod it does add some strength. Problem is the block isn't going to break anyway, so why waste the time?

We have broken blocks, not where polishing would help though. We have split the cylinder walls and have actually had the blocks split between the cylinders the complete length of the block.

All I am trying to tell you guys is the 4g63 is just an amazing piece of work. The complete engine is WAY over engineered. I am still using a stock block, head and crank in all of our race cars here. The tube chassis 4g63 has gone 7.8 at 175 and the 4g63 powered Conquest we have has gone 8.7 at 151 mph in street trim. These cars run an automatic trans with VERY loose inefficient torque converters. Both of these cars have slippage in the converters of 17% at 9500 rpm. Even with this being considered the Conquest with a small internally gated turbo has made 665 hp to the wheels and the tube car has made 776 to the wheels. Flywheel HP in the tube chassis car is approaching 1,000 hp.

Something to consider.

David Buschur
www.buschurracing.com

 

stress relief and polishing a block will make the piece stronger and more reliable, easier to clean too . For racing purposes that is. On the street there is no advantage. There have been DSM's in the mid 1990's that went into the 10's with no shortblock work. Stock internals. If you can afford it then do it. I for one don't have cash for the minor details like this, therefore there is no way I would throw down over $1000 just on polishing and stress relief. But thats my budget. I dont beat the **** out the car EVERY day, so reliability should be ok for me on the stock set-up. Nice work on the block though

 

My post was also one to educate and to show others that money is better spent elsewhere.

Sorry, there were some pretty silly statements made on the first page. I'm just keeping things in check here.

The broken piston picture didn't even come from a 4G63, and it isn't the sort of thing that happened because of a cracked block, so why even post it? You guys said to make people aware. Aware? Aware of what bad tuning or machining will get you?

I do appreciate the pics you posted of the block. It is interesting to see the changes.

 

Yep, the later 4G63Ts (known as a 7-bolt) are probably more rigid because of the girdle.

My block is out of a 1991 Eclipse. It is a 6-bolt 4G63T. 6-bolts came with larger rods than the later 7-bolts. You can see a 6-bolt rod on my web page. Compare it to an Evo's rod. I bet the 6-bolt rods are larger. The 6-bolts were only made up to 1992.

Nearly every DSM that is serious about racing uses the 6-bolt blocks. The newer 7-bolt blocks tended to wipe out thrust bearings in short order and would not tolerate a stronger clutch.

 

Incidentally, the rods in my engine are shot-peened and balanced 6-bolt rods with 2G DSM pistons on them, and ARP rod bolts. I knew I'd never exceed the stock 6-bolt rod strength, so I used them. People have run low 10s on these rods. I know about stress relief. I just choose to use it where it will make a difference for my application.

 

David , you are the man when it comes to pushing the 4g63 power factor ! ! no argument there ! ! this is going to be a "fast" road car , not just a 1/4 mile car ! ! so I need to have nice and light reciprocating assembly .. not just to hold together for a 10 second pass.. but 30 to 40 minutes of road racing ! ! driving to and from the track etc. etc.

 

To go back to a post made yesterday when someone had questioned that validity of putting that much work into a car that is only worth $30,000. I posted that picture just to show what can happen, and that can and has happened to people's motors for a variety of reasons. All I was trying to do was to show that no matter how great you think your engine is to begin with, thingts like that can happen, I was not saying that they are guaranteed to happen.

 

This is the same stuff I have heard from Dan at Pruven and one of the major reasons why i jumped from WRX to EVO - - time will tell !

My Ferrraro kid build stock block Evo motor is going strong with 4,000 miles - again time will tell !

 

I am not trying to start a battle here, or say who is right, or who is wrong, but the interesting thing that I find, and this does not apply to all of you, is that some of you will go out and spend more money on exhausts, intakes, throttle bodies, cam gears, turbos, intercoolers, wings, wheels, springs, etc. that when it gets all added up, will surpass the price of having the work done on the block I was referring to in terms of blueprinting. But there are no complaints there, right? Its fine to spend about $10,000 on bolt ons that give you something here and there, but to spend any kind of serious time and money on trying to give all those upgrades a solid block to work off of, well, that is a waste of time? I just think that for some of the applications people are looking for, using what comes out of the box as a platform for lots of boost, big turbos, NOS, and so on is lacking.

 

no one can disagree with building a good foundation...youre on the right track as far as I can see...

 

My engine was definitely the largest part of the mods I have spent on my car.

I have no cosmetic mods. Well, just the rims, and I spent all of $350 on them. They are 16x7 instead of the 17x6.5 that came stock. I actually like the looks of the stock rims more.

My RSR turbo-back 3" exhaust was $450 used.
My Evo III 16G was $570.
My 2.5" tubular O2 housing was $180.
My front mount intercooler was $475 with the tanks.
I welded up my own 2.5" intercooler pipes. They are painted bling-bling gloss black.
My HKS 264 cams were $400 used.
I ported my own exhaust manifold.
My SFI1.1 ACT clutch was $400.
My SFI1.1 ACT flywheel was $260 (no exploding lightened flywheels here).
My injectors were $280.
DSMLink was $470.

All labor was done by me.

And the engine cost me a bit over $2000 to build. And I built it with my own two hands. The only machine shop labor was the hone-job, and rod work. They measured each piston and matched each one to a bore. Oh, and the balance shaft bearing block-off installation. I have since done that myself, but I couldn't find the right tool in time to do it for my own engine.

You are eliminating the balance shafts, right? Since the balance shafts spin at 2x the engine speed, they are a really bad failure point.

 

To reply to David, with all due respect, and no candor intended:

"The statement that the 4g63 block isn't good for high horsepower without major machining is quite frankly complete bull****. Now the fact of the matter is that the machine work that IS required when building one HAS TO BE done correctly or you will be screwed."

That is you opinion, and you have built many more of these engines than I have for sure. But after measurements and data collection on this motor, I find it to be severely lacking in terms of dimensional quality for what I consider to be a good platform for building a race motor out of. Thats my opinion.

"The major lightening of the crank that I see here not only is a waste of time in my opinion but will cause problems in the long run. There are quite a few guys that have tried this already and have nothing but problems. Polishing of the inside of the block is another area that just isn't needed. Yes, like a rod it does add some strength. Problem is the block isn't going to break anyway, so why waste the time?"

I have not worked out the percentage of weight, but so far I have removed 3.5 lbs from the crank which started out as a 32 lbs unit, and done a true knife edge. WHat are the problems that you have seen with taking weight off of a major rotating assembly in an engine and who has done this modification unsuccessfully? THe other thing I don't understand is that you agreed with the fact that polishing can increase strength, but why do it since the block isnt going to break anyway? But then I go on to read your next sentence which states-

"We have broken blocks, not where polishing would help though. We have split the cylinder walls and have actually had the blocks split between the cylinders the complete length of the block."

ANd then after all that, you say-

"All I am trying to tell you guys is the 4g63 is just an amazing piece of work. The complete engine is WAY over engineered. I am still using a stock block, head and crank in all of our race cars "

Your terms are a dichotomy. I am not challenging you.
I thought that this internet thing would be a good way for everyone to share ideas and information and to help better the breed. Not get slammed for trying to raise the bar and just settle for leaving good enough alone.

 

I am going to post a series of pictures to show what I mean, they may be a bit boring. It is a series of shots taken of the main cap assembly from a 4g63 that had less than 1500 miles on it. SO consider it pretty much a new engine that had barely been broken in. Each shot will show a dial indicator running down a few of the cap feet where it mounts into the block next to the main saddle. If you think this was bad, you should have seen the block surface for the same thing.

 

start here with the peak of each main bore