Those who know? I feel like I do know. Again, I'm not in it for quarter mile times, I do 20 min sessions on my local road courses, I do autocross and I drift, none of that is for timeslips; it's for fun and I want the car to be more fun for me. My chassis and I personally can handle at least 20% more power safely and feel the way I want it to feel which is with stock like throttle response, that would be over 500 on the SAME DYNO.

 

Dyno numbers don’t relate to the street, the road course or the drag strip.. They sound good though.

Car sitting stationary on the dyno is just not the same. You always have to adj the AFR. Unless you have the air intake in the drivers compartment.

 

I think the camshaft has way more influence on where power is made and how much vs the cylinder heads. That's assuming you're comparing decent square port and catty port heads and not dealing with a big cam. Keep the duration mild, static and dynamic compression on the high side, lift on the high side, and you should make decent power all through the band. There shouldn't be any loss of low end power vs a stock setup. Hell, the general puts square port heads on truck engines.

I have 295 width Michelin PS4's on my 2013 narrow body Vette. No, not as good as an R compound competition tire, but one of the better street tires out there. Depending on temp and pavement type, they don't have a chance in first gear rolling into it at just about any RPM. They will get loose in second a lot of times too. You also don't get the "lazy 'till 3500 rpm" business that you get with most bigger cams. It pulls a little harder past that, but not as noticeable because it's pulling really good below that.

I can see, dealing with a bigger cam, where a smaller/higher velocity intake port would have low end advantages. I just don't think that applies when you're comparing them with a smaller cam. An LS3 comes with a good set of heads and intake manifold. Buying a high dollar set of heads along with a high dollar intake manifold would be a deal killer for me.

 

Look at LS Poncho's LS3 Build .
550+ RWHP with MMS Ported OE Intake & TB, Schmedium Cam ~229/243, MMS LS3 Heads (AFR Castings), and
~28 lb MMS RPS BC2 Dual Clutch/Flywheel Assembly.

As someone who spent A Lot of $$$ on a custom LS3 Headed Engine, I can tell you to have a legitimate 500+RWHP
stock stroke LS3 WITH Fantastic throttle response and Great Drive Ability every where will take some Excellent Heads and the right size cam.

My suggestion, for what it is worth, AFR LS3 Heads out of the box with a lighter hollow intake valve, and
The Cam Motion LS3 Titan 3 227/237 113 and Milling with .041 Gaskets to achieve ~ 11.3-11.7:1 comp. tight quench ~.035-.040
depending on 91 VS 93 Octane availability, I would expect ~520 RWHP with a good tune and fantastic throttle response,
along with exceptional low speed/RPM driving manners.

It costs more to "Have Your Cake & Eat it too."
Just my .02

 

Im right there in the neighborhood with GPI ported ls3 heads milled .040 with .041 gaskets. Just over 500 on 93. With e85 sorted out i should be 500+

 

Did a road trip to Spokane today. I got 29.84 mpg on the way. I think when the new gears go in (3.23 vs. 3.73), it’ll get 31 or 32.

Not bad for a car this scary fast. 🙂

 

Nice!

 

I thought I'd posted this, but I guess not. In late May, I finally got the 3.23 rear end gears in to replace the 3.73s that were in there.

Highway mileage went from 29.8 mpg to 31.2 mpg on my standard "trip to Spokane" measurement loop.

The car has been running a bit over a year on the new engine, a bit over 200 hours, so probably 9000 miles (no speedo or odo in the car, just a tach with an hour meter, because racecar). It's well mannered, smooth, gets great mileage, and is scary fast. I drove down the Oregon coast on US101 to see my Dad in early September, a 2000 mile round trip.

This build met my goal of a usable, stupid fast car. Thanks again to Tony Mamo for his parts and input.

 

You have the best of a few worlds. Laundry-soiling performance, yet behaved when called upon, plus cruise economy quite close to that of the OEM 4-banger. Stop and go, maybe not so much... lol

 

Yeah, 30+ highway, but city is nothing to write home about. 8 cylinders worth of ring drag, bearing drag, etc ... I'll take it.

A rough estimate is 5 mpg/gear. So 5 mpg in 1st, 10 mpg in 2nd ... 30 mpg in 6th.

 

First track day in 6 years of driving this car, at Ridge Motorsports Park in Shelton, WA. Full report below, TL;DR version ... car ran great, it was a blast! :-)

The track day went very well. This was my first time on track in one of my own cars in 18 years. This car has 3x the power to weight ratio of the SC MR2 that I tracked previously, so it was a very interesting day. It took 2 hours to get to the track, I left the house at 4:30AM in order to be there before 6:30AM. The first meeting I had to be at was at 8AM. I like to get places early, but I'll probably leave later next time.

I ran 4 of the 6 sessions available. The track layout used included a chicane in the middle of the main straight, which kept top speeds down a bit. My instructor signed me off to run solo after my 4th session with him, but then I found I had a broken muffler hanger. I did a quick fix with zip ties, but I didn't want to take a zip tied exhaust on the track, so I called the day a win. The goal was to go fast enough to shake down the car, and fast enough that I could start trying to get used to it, all while being able to drive it home at the end of the day. I did all that, so I was happy with how things went. Some sections I went pretty fast (probably got ~130 mph on the shorter than usual straight they were using today), and others I left a *lot* on the table (a section where my car might reasonably be at or a little above 120, but if you mess it up you don't get to drive the car home). I'll start pushing those sections after a few more track days. Unfortunately, I have no video or data of the day. There seemed to be enough things to juggle getting in the car and ready to go on time for each session without adding that. It's more complicated with the instructor involved. My guy was 74, so was maybe not as agile as some in getting belted up, getting the inter-helmet comms going, etc. When it's just me, and I have a system in place, it'll go better.

Overall, the car is very sweet to drive. It's not trying to bite me, very predictable. The brakes worked great, no fade all day and tons of deceleration available. I was a bit worried about this, because there's video on YouTube of a V8 Miata fading it's brakes within 2 laps at a track day. Apparently, my ducting, heat shielding, and expen$ive pads worked. I could certainly have been more aggressive with my braking in a few corners, it will take a bit to get used to really pushing them. They are extremely capable.

I had planned to use mostly gears 3/4 on the track, because on the street, 2nd is usually very hard / impossible to keep out of wheelspin. As it turns out, once the track tires got hot, the car hooked in 2nd just fine (having the extra ballast of the instructor in the car probably helped, too). In 2nd gear, the car accelerates at about 20 mph / second, so 40-80 mph in 2 seconds coming out of slow corners. Tons of fun, thank you Tony Mamo! In general, I really enjoyed the tires. It's been a **long** time since I've been on hot track rubber, and I'd forgotten how capable it makes the car.

I hit the rev limiter (7000 rpm) several times in 3rd gear when the tach was only indicating a bit over 6500. I don't think the tach is inaccurate, I think that when the car is accelerating hard, the tach needle just can't keep up ... I'd noticed this on the street, too. I'll probably have to shift at 6200 indicated from 2->3, and maybe 6500 from 3->4. I won't need 5th on this track layout, because 4th is good to 145. If I ever run here without the chicane in place, I'll need 5th gear. The car pulls hard all the way into the limiter, no feeling of reduced acceleration above 6000 rpm.

Fluids were all good all day. Maximum oil temp that I saw was ~250 degrees, so the cooler seems to be working. Oil pressure can be a problem in LS motors in sustained left hand sweepers at over 1.2G ... one reason this car only has 205 section tires on it, and no real aero ... it keeps the cornering forces a bit lower. I peeked at the pressure gauge in the middle of turn 6 (a long left sweeper) and it was fine, 50-60 psi. I didn't use as much gas as I expected to, maybe 8 gallons on track in 4 sessions, at the most. I added octane booster to the gas in order to give my engine a bit more margin against knock since it'd be hot and under sustained high load. I don't need it on the street, because I'm an old man.

I only scared myself a bit once, braking into turn 6. I'd come out of 5 better than I had previously, so I had a bit more speed coming into the braking zone. The back end of the car was moving around like crazy under the brakes, and acting like it wanted to let go to the right. I used **all** of the track gathering that up, but didn't go off. In retrospect, I suspect I had a little steering lock on when I applied the brakes ... not a good idea if you're braking really hard. I will pay attention to this next time I'm there.

 

Great to hear. It’s a huge sense of accomplishment being able to race what you’ve built. I never got to drive for others, and only drove my own stuff, but I felt good knowing that I knew the car inside and out, and if I take it home in a box…which I did more than once…there was no one to be mad at me except the wife.

 

Sounds like an excellent safe exciting day at the track!

Here's to many more!

 

Outrunning the tach. That's next level badassery right there! Glad you're enjoying it

 

Nice job Mike! Thanks for the report. As Chevelle said, successfully tracking a car you built yourself is extremely satisfying and makes all the effort worthwhile!

Ron

 

Yes it is!!.....LOL

Most tachs have a dampening system built into it so its needle moves smoothly but a really good build can accelerate faster than the tach can now keep up due to that dampening system

I experienced this with my first really good naturally aspirated Big Block build in the 90's (850 at the flywheel).....couldn't understand why I was banging into a 7200 RPM chip at 6900.....LOL

And this was a "Sun Super Tach II" aftermarket tach (Im dating myself now!!).

Ended up putting in a shift light which went off exactly when it was supposed to.

Honestly to all you guys reading this that dont own one, once your making good power you should be paying more attention to the road than the tach and the shiftlight allows you to do just that.

Mike.....get one so you can pay attention to the curves and braking markers.....you shouldn't be watching the tach! Set it a little early if you want a heads up your close to redline.....its infinitely adjustable.

Enjoy the car.....sounds like you had a blast

Regards,
Tony

 

A couple of pics from the track day...

 

How often does the steering wheel come into play? Just enter the turn and do the rest of the steering with the throttle?

 

Just got back from 2500 miles in the Miata on a two lane road trip from Seattle to the SF bay area and back. I met up with NAVYBLUE210 (Dan) at his house near SF. The car ran great, though at one point I picked up a rock via the brake ducts that was making a noise between the rotor and the metal rear disc shield that is part of the brake ducting. Took about 10 minutes to diagnose and fix ... I had tons of tools and a full size spare in the trunk.

The weather was much better than it's been in the Seattle area so far this year. I got a bit of a sunburn, because I had no base tan at all, even though I drive this top down 99% of the time here at home.

No stereo in this car (or A/C) ... I didn't miss either. The steering wheel and the gas pedal provide the entertainment.

 

Looks like a blast. and no joke about this weather. ugh.