Greetings!
I have been holding out posting this until I got a little further along with the build, but now is as good a time as ever...
When most people think about adding power to the venerable 5SFE, they think of adding boost, or sometimes a blower. More rarely some will consider adding a shot of N2O...but what about N/A builders? Where are they? Since I know of only a handful of guys that have been successful with building a naturally aspirated 5S motor, and they live mainly on the MR2 forums, I figured I should share a current work in progress with yall...
The goals of this build are twofold - Retain daily driveability but also have the snappy throttle response of a properly built N/A engine to boot with a quick downshift. We all know that the redline of the 5S motor is 6300 RPM - not really conducive for power making. So the first thing is to build reliability above that range and well into and beyond 9000 RPM.
Starting with the bottom end are some specialty JET titanium rods which I bought used for $400 and were found to be in great shape (kinda rolled the dice here I know, I got lucky!)
These rods are used in midget cars with a 2.7L motor with a 11000RPM redline - much higher than I plan to go with it! They also feature 7/16th inch bolts for less high-RPM stretch. The stock 5S rod is on top...
However, I ran into a problem very early on in the build - the rods were 6.000" center to center length. Stock 5S rods are 5.433" long...hmmm....
So I decided to destroke the motor .450" total in order to make these rods work for me. I realize I could have gone the other way with different sized rods, but for $400, I was already committed and found out later that this was not a bad idea at all. I found an aftermarket forging which was 38.4 lbs with standard bearing sizes opposed to the 41 lb stock 5S factory crank - with the destroke and knife-edging it may be close to 30 lbs which will be great for my application.
Furthermore and most importantly, these Ti rods weigh only 452g each - and just so happen to be big end and small end balanced to 100mg between rods - stock 5S rods are I think 680g apiece - that's a MAJOR rotating/reciprocating weigh reduction there which will translate into much more power at the wheels in the first two gears. But the weigh reduction doesn't stop there...the small end of the rod measures .929" which enables me to use titanium DLC coated wrist pins weighing only 77g each. Stock 5S wrist pins weigh 130g each.
Pistons will of course have to be custom built, and I am looking at a CR of 12.5:1 plus or minus .25 to 1. Stock pistons weigh 360 to 365g each, and the customs will likely weigh between 250 and 300g apiece, hard to say with the increased CR though.
So the bottom end will see a weight savings of at least 10 lbs for the crank, 2.1 lbs for the rods, and almost a half pound for the pins. The pistons are not built yet so I can't even try to speculate on those. The long rod/short stroke of this motor will load the cylinder walls much less than the stock motor which should help bearing life and reduce friction. Another benefit of the long rod ratio is increased dwell time at TDC. This translates into less need for advancing ignition timing - which reduce chances of detonation (especially with the 12.5:1 CR)
The cylinder head will have to be the masterpiece of the motor - much more work will go into it than the bottom end. I was lucky to get a hold of some used titanium valves from an IRL builder which were 6mm stemmed. The heads are obviously too large for a direct bolt-in, but I have lathe skills and plan to use them. I am hoping to turn these down to 2 or 3mm oversize both sides, and use shimless buckets I bought from a guy in Ireland for only $1.25 apiece!
The exhaust valves will be a little more user-friendly; the intake will require a little more work. Titanium likes to bond with carbide if you cut too fast, so machining costs are a little elevated
Reducing reciprocating weight from the valvetrain will also help with high-RPM power and serve to extend the powerband a little more before valve float occurs. These valves may need to be ZrN coated to help with heat resistance and corrosion, especially the exhaust side, for longer life. Titanium valves are the most advanced material available I know of currently for the application, and a good coating will ensure long life.
Another thing I learned in the MR2 forum was to make an adjustable cam setup for the 5SFE, thanks to mrturrari. I haven't progressed that far into the build yet, but the main idea is to make each cam independently adjustable; namely the intake to lessen reversion with the long-duration setup I plan on using. I want to ATTEMPT to balance streetability and high-RPM power, and I know the 2zz does this by the VVT-i (which I won't have) and higher CR (2zz is 11:1 IIRC). May be able to circumvent this partially with the titanium valves - their lower recip mass should allow for a more aggressive profile while the intakes can be opened/closed quicker to reduce reversion (just a theory though). So the cams will need to be a total custom job to make the most out of the lightweight valves, there goes another $800 at least!
No N/A build would be complete without some kind of porting/polishing, and that's where most of the focus of cylinder head work will come into play. 5S cylinder heads have PLENTY of material to work with - the main idea is to make everything larger and smooth out any transitions, bumps, casting flash, etc. If you can envision water flowing through a passage - any bump or impedance will slow down the rate of flow. Air is a fluid as well and behaves in exactly the same manner, although it is much less viscous. Everyone will tell you that a Dremel tool is the porter's best friend, and this is true; but EXTRUDE HONING should be a next-to-last step for the highest-quality portjob. This process will go where the Dremel can't and remove stuff you never knew was there. Plus, the abrasive media will cut tiny longitudinal lines into whatver is being ported (intake, head, exhaust manifold, etc) which will actually promote airflow in that direction.
There is nothing that can substitute for Extrude Honing - to do a PROPER port job do the Dremel work first and THEN get the honing done. Works exponentially better with boosted and blown motors...there really is no substitute!!!
In the coming months I will keep everyone abreast of the progress - it will be a slow agonizing and tedious process, but bear with me - it will all pan out. If you do not want to wait and would like to see some ideas for a decent 5SFE portjob then I suggest visiting the MR2 forums and searching the posts. Mrturrari has some excellent insight into the 5SFE head and has outstanding pictures as well - I will be posting pics as the build progresses.
95 Camry
Piece of Crap
Looks like you'll be doing this build the right way.
. Don't know if I need that kind of tensile strength - only going to be pushing a little over 200 HP at best so probably not going to need those...
AUTO to MANUAL Swap Guide (3rd Gen) - 
), and then shrink the rod journals to the .861" measurement. No destroking or any of that mondo-expensive stuff - still looking at a pretty penny for all of this, but the 357g WEIGHT MATCHED set of rods is almost 100g lighter than those SBC 6.000" rods I had originally planned on using...
. Would only have to mill .0015" off the bar stock to make it work. Then the difference in compression height could be made up using custom JE pistons - this is where I could possibly have a 2.3L 5SFE - Hmmm...
1991 Toyota MR2
1996 Toyota Camry
1993 Toyota Camry
Linear Mode
