RX7 Hillclimber Build Thread

learned some lessons applying the vinyl to my hood. Love the color though so I'll proceed with the rest of the car once I fix some body boo boos

Welp, 2nd time in a row I got wait listed for Mt. Washington. I thought winning a hillclimb season championship would help my cause, but nope.

SO. I'm giving up on the dream of running a rotary up Mt. Washington. Enter a new engine dubbed "Don't Hold Your Breath"



Due to classing based on displacement, I wanted to stay under 5 liters. This one's a 4.8! Given my goals of peak 400hp this engine is ample and with the shorter stroke she should be revvy. I got the whole engine, tranny (4l60E) and transfer case for $400. I got rid of the tranny and transfer case because BLECH. 

Getting ready to send the short block out for a cleaning and replacing cam bearings. I saw a little wear on the cam and I want to just make sure that whole system is good. It's likely the plastic lifter holder allowing a little bit of twist. 

Good news: with something like 170k miles she looks decent inside. 


Those header bolts aren't going to survive one second under a removal device...

New shirt is nice though

Those headers are impressively rusty.  The level of rust you guys get back East still amazes me.

Living in a high plains desert has it's advantages.  I literally leave steel sitting outside and it doesn't rust very quickly.  Nobody is throwing salt on it either.

TVR Scott said:

Those headers are impressively rusty.  The level of rust you guys get back East still amazes me.

Living in a high plains desert has it's advantages.  I literally leave steel sitting outside and it doesn't rust very quickly.  Nobody is throwing salt on it either.

 Yeah sadly normal looking for the northeast.   

Happens out in the midwest too :( 

It's what I think when I see people have salt life stickers on their cars in my area haha.

What you need you is a bare 5.3 block to swap all the 4.8 bits into.  Do a car-part search for an '03ish Ranier 5.3.  Those were aluminum, and had the worst cylinder heads and connecting rods, and a non swap friendly oil pan.  So they are not a very popular engine for swappers.  If you pay $600 for the engine and recoup $200, then that $400 for the block is five bucks per pound of weight saved compared to an iron block.

He has to stay sub-5L due to classing requirements I'm pretty sure...

Edit: or would 4.8 bits into a 5.3 block actually yield an aluminum 4.8l displaced engine and I'm just a moron...?  

In reply to golfduke :

That is the idea.  The 5.3 and 4.8 have the same block, the difference is the the stroke.  The 4.8 is the only common engine with a different stroke from the 5.3/5.7/6.0/6.2 engines.

Chevy never made an aluminum 4.8 but all the parts are junkyardably common to DIY.

Alternatively, I wonder if you could remove even 40 pounds of excess iron from an iron block engine.  There's lots of casting knobs and excess bosses everywhere, and running a used block means you have a perfect impression of where the gasket surface O-rings are, so you can mill away the areas around that.

Cool!  Today I learned!!!  Thanks! 

I'm going to have to add ballast for NASA TT anyway (about 200lbs), so a little extra weight in the block doesn't bother me.

I'll keep an eye out for an aluminum block, but it's lower on the priority list. The block castings actually say 4.8/5.3 right on them @GolfDuke GM Legos.

Last night I pulled the manifolds and only broke ONE stud. Which means I have 4 studs to remove since 3 were already broken.

Inside looks pretty good. Carbon-y, but some cleaning and a light hone will have it right as rain.





I ordered a spring compressor and a harmonic balancer tool to continue the disassembly

There was some wear on the cam I didn't like. Looks like the plastic lifter trays are bagged out and allowed a little bit of twist. No pics of that.

Replacements are cheap though so who am I to complain. Vacillating on cam choice. Leaning toward LS6 with beehive springs, stock rockers with upgraded trunion bearings and some heavier wall pushrods.

If the car is 2400lbs I'm allowed 370whp (ish) for NASA TT1. Right now the car is 2200lbs with me in it and 210whp.