Gregg, if that's the range you wanted your gears to cover, then with a MR intake and a useful rpm range to 6000rpm you would just jump to a 4.11 gear. Given that torque at the rear wheels is what determines your instant acceleration, then doing the math shows you'd have much more acceleration in the same speed range and still have a wider powerband.

I haven't done that, largely because I like the very tall 2nd gear for autocrossing. Well, also because even with the stock gears and my "high rpm intake" I can't hook up 2nd gear on any street tire not intended for competition. First gear is hopeless. So more gear would really be a waste on the street for me. On a 60mph freeway (where, let's face it, we're all probably driving 70mph or more), if I just need to pass someone I leave it in 6th. Even though 2nd is good to 79mph at my stock 6400rpm redline, if I need to go fast I go to third and pull to really illegal speeds. It's all easy, and fun!

 

Don't think I haven't considered a swap to 4.11's. And, to swap in my HSR. But, as posted in my last post, I'd need to decide if my build will tolerate higher rpms (discussion linked in that prior thread). I'd also have to decide about funds for the gear swap...and potentially for a new crank.

It all costs money...which was the other point frequently made here.

 

We agree on that! Which is why I advised the OP that only he can decide if it's worth it, given he already has a ported TPI.

 

All builds should handle 6000 rpm, factory parts can handle that. If your build cannot take 6000 rpm you need a new engine builder.

 

If your going to build a motor why would you want it only making power to say 4500 rpm's?!? We have diesels motors if you want a "stump puller".

 

This was the exact reason I stayed with a TPI style intake when I built my 383. I already had AS&M runners, an Accel intake and a ported plenum on my stock 350. I knew the downfalls of staying TPI and I'd still have option of changing the intake down the road. I also wanted to see how the 383 would run with the TPI on it. BTW, it now runs high 11s in the 1/4 which is more than fast enough for me since I don't want to put a cage in the car anyway.

 

Your engine looks good and runs very well.

 

Now you know why I haven't posted a question about the viability of the build sooner. I'm guessing there's only a handful of builders (in the country) that know whether my combo was a bad approach or not. I didn't say it WOULDN'T rev to 6000. Geez. It's bad enough to get this type of feedback from speedtalk. It's truly amazing how well I anticipated this kind of (unhelpful) feedback.

 

I didn't see what trans you have in that car. I assume ZF6? That's pretty cool 1/4mile times for that modest cam. There are plenty of cars with more cam than that but moving slower. Nice combo

 

Nice looking motor TA. I am also staying with TPI.I would like to Know more info on your 383 TPI Build.

 

A4 , 2500 stall TC and D44 rear with 3.33 gears

https://www.corvetteforum.com/forums...o-results.html

 

I am sure Tom will throw a Miniram on it one day.

Vic

 

You Da man TA.11's with ported 113's a 219 cam ,auto trans and TPI.Great thread.I reread the build thread and forgot it was done on a mail order tune.

 

Yes and turn his trap speed from 108 mph to 114 mph.

 

The intake you choose depends on your application and rpm range. 1/4 mile where the rpms are ran out to 6500 to 7000 the MiniRam is going to be a better choice. Tracks with mainly long straights are best for the MiniRam. Get on an autox without long straights or a track with multiple corners and short straights; high flow TPI will have an advantage since RPM's will most likely linger between 2500 and 4500rpm. For the street; who maxes the rpms out to 6500? Hell, I know you all have LT's and free flow performance mufflers

No matter what intake someone chooses; the proper cam profile, heads, and rear ratio's need to be chosen to promote that intake.

 

Well, as I've noted earlier in this thread, I have autocrossed TPI cars and my current ported-LT4-intake car, and my experience is that the TPI car (a Camaro with considerably shorter overall gearing in 2nd) ran out of breath a lot. My 396 LT4 gets well above 4500rpm (55mph) pretty often at events with my stock 3.45 rear gears. Granted, this is course dependent, and some areas tend to have tighter courses than others. But even if that's the case, if you run in a class that allows stroker motors then you are allowed to change rear gears. And that would be an obvious thing to do if your courses rarely exceed 55mph. Again, a jump to 4.11s would put you in autox nirvana with an short-runner intake at those speeds.

Anybody with a short-runner intake and a soul.

 

Greg, I am not trying to hammer you but you are over thinking this, i read your speedtalk post and the real question was not answered. You want to know if the way your engine was balanced was OK and will it live fine if you rev it higher. The answer is yes the way your engine was balanced was OK and (Sure you could have used a forged crank and internally balanced it) will work fine in a 6000 and under RPM set-up. There have been many thousands of 383 built with cast cranks and external balancers, plus many more thousands of 400 chevy's built using the same practice. If you want to try the stealth ram put it on and see how it performs it will not wreck your engine. If you are nervous just ask your engine builder, but I am sure it will work fine with the cats crank and external balance as is.

Back in the 1980's we ran 410 sprint car engines with stock factory blocks and cast cranks that were externally balanced with 600 HP and 7500 RPM. Sure they eventually broke but they would last a season like this and that combination is way exceeding what you are thinking about doing.

 

I've had an LT4 also. For 95% of the autox's I ever ran; my High Flow TPI was a better choice and would out perform it.

I haven't hit 6500 rpm on the street with my Z. The quicker to the next gear; the quicker the acceleration. Plus, I was referring to the sound dcb at the higher rpm. In the younger years I learned that loud high rpms attract the men/women in blue.

 

SWEET

 

OK...Thanks Brian.

Let me ask you this: Do you think an externally balanced 410 sprint engine has more vibration than an internal factory Chevy? I'm not talking about light-years difference, I'm just asking. In 2010, after talking to the local engine builders, I was told that a hand-built 383 would be better, smoother, faster -- and jump tall buildings in a single bound (as compared to my original 350).

I finally found one problem with the side-pipe mounts after a few years...but I had to buy it used, had no directions, and had to wait 2 years just to find that unique system. (I like pipes on the C3's!!!)

Currently, it has a mild miss or imbalance from 1600rpms - 2200rpms. It's factory smooth from 2200-3500. Either I have an injector imbalance, ported-intake imbalance, spark wire issue, or even an odd combination of these, motor build, and/or even the crank. Because I used a small cam, I expect it to be smooth. In fact, it will idle smooth a 750 rpms....like factory smooth.

I kind of think the imbalance has been there since close to the beginning. Certainly, it's had more of a "lawnmower" type vibration than the original 350. But, the AMOUNT of vibration is clearly rpm dependent. In some regions, it's VERY smooth. The fact that it's not ALL regions is why I have to ask....especially when my expectations were higher during the project.

I think I'm also asking if a self-ported intake could be the culprit? Just as much as I might be concerned about putting an HSR on it -- due to vibration, I also have to be honest and say I'm curious if the HSR will CURE the mild vibration I perceive. I am certain the ports are even and symmetrical in the HSR. I am also certain my hand porting isn't CNC perfect. Plus, the SLP does have it's limitation in the end port tubes (mounting bosses create a pinch).

I've had multiple people say my build is "unusual" -- but fine. And, I've also have as many say an unevenly cast (or ported) intake WON'T cause vibration. This is part of the reason I've grown to be uneasy about it. (Yes, I've asked the builder and he says to keep looking elsewhere.)

I gotta say it seems more logical to assume the intake causes the issue. Logically, I have some inclination to wonder about my [inherently] imprecise hand-porting...and it effects on engine smoothness. There are ONLY two cylinders monitored by O2 feedback due to the location of the bung in a Tri-Y header. Maybe those tubes are running 14.1 AFR...while another is lean enough to cause problem? Maybe I'm getting significantly more air through other tubes? Due to the nature of O2 feedback, it would be hard to retune the chip to run richer -- and see if it ran smoother. BLMs are always going to force the engine back to (what it thinks) is equilibrium.

That said, there's a "builder of fine engines" in Speedtalk (Walter Matlik) who thinks my motor is trash and will throw main bearings. Of course he said that 4 years ago...and is still be a butt-head poster about it today.

I don't know if the "best" are smarter....or sometimes just have an attitude? If he's the one that's "full-of-it", knowing it will help me make better decisions...and possibly convert to the HSR -- BOTH to see the difference in performance...and smoothness.

Maybe I'd be the one to show hand-ported intakes aren't all "perfection"! LOL

But, how many of those 400's had as much weight pulled from the counter weights? Walter Matlik posted this (about my engine) back in 2012:

Drilling a bunch of large holes in the front and rear counterweight to remove the excess weight will get it ROTATIONALLY in balance however, RADIALLY along the AXIAL centerline of the crankshaft will more than likely not be near correct as one of the secondary waves of balance will become even less correct.
The unkind waves will lead to more flex and eventually the crank will show cracks somewhere because of this. This usually is evidenced by excessive #2 and #4 main bearing fatigue in a V8 engine.
Lower RPM and lower power generation will of course lengthen the time it takes for all this to happen
The effects of incorrect RADIAL balance can be seen in a crank which needs center counterweights, (or not), even though they won't change ROTATIONAL balance at all or very little at the most.

Those holes can be cosmetically ugly however, that is NOT the only problem with it.