skipnsb

Project: street only 406/stock crank/hyperteutic pistons, + heads/cam (not sure yet) 6000rpm max.


I just bought a Super Ram Plenum/Runners and 52mm Lingenfelter throttle body ($100 used on local c/l, 3 blocks from work!). It looks like the only aftermarket tpi made now is the First and they will not sell me only the manifold. I would appreciate your thoughts on buying a used Accel/Edelbrock/??? vs. porting the stock intake manifold. Do I understand correctly that the intake manifold will be the bottleneck no matter what?


Can a ported stock tpi intake flow like the aftermarket?


If I am looking for a used aftermarket intake, which would I look for? Or they all about the same once ported?


Essentially, should I look for an aftermarket intake or just port the stocker? Thanks Skip


ps I could not find the answer by searching, if you have a link to comparisons between ported stockers and aftermarket please advise. I did find Grumpyvette's postings comparing the aftermarket to the stocker, but nothing on the ported stocker.

Vader

Welcome Aboard!

A 406 is going to take all the flow you can give it. Even a ported stock base could be restrictive with a Mini-Ram. That style intake is pretty open, free-flowing. A Super Ram still relies on the long runners and might have its own limitations with or without the stock base.

ULTM8Z

NO way would I ever put a TPI style manifold on a 406 unless all you wanted was neck snapping torque below 4000 rpm and nothing else...

BadSS

The FIRST was designed from the ground up and the GM style TPI parts will not bolt up to it. It can be welded on and modified to work with the GM TPI runners, but by the time you do all that I think you would be better off selling all the other TPI parts and going with a complete FIRST system.

A stock intake (around 220cfm) can be ported to flow about what an unported aftermarket intake will flow (around 245cfm). It takes a lot of work and if you can’t do the work yourself, it’s almost not worth the cost to pay someone to properly port it. Used aftermarket intakes are going for a premium since they’ve quit making them and without welding on one a fully ported one flows around 275cfm.

Once the FIRST became available, I never understood people that didn’t have to have a CARB exemption paying $450 for an aftermarket TPI intake and then paying someone $300 or more to port the thing when you could buy a complete FIRST system with throttle body for $1000 that flowed more (around 300cfm).

It takes putting money in the heads and a lot of work and planning to prevent a 400 with a TPI system from dropping off past 4500 rpm – but making peak power in the 5800rpm range is not unheard of. There’s no perfect fixed intake runner out there, but the Holly StealthRam will make a better fit than an aftermarket TPI or FIRST in most cases. However, a TPI style intake on a heavy car with an automatic, low stall speed, and highway gearing could be a better fit. It all depends on what you want to accomplish and what compromises you’re willing to make.

skipnsb

I have a 1989 Corvette convertible, no racing, no autox,full ac, weekend toy just to run around. The 406 and Superram fell in my lap, so I will do an exhaust and heads (afr/promaxx?) and probably a near stock converter. So yes I understand I won't be winding it up, a 6000rpm redline is fine, I accept that the C4 is faster than I will ever be.

I will port the stocker if I have to, but if I look, which aftermarket intake would be preferable for a street Superram? Thanks

skipnsb

...and thanks on the heads up that the First won't work with the Superram.

Tuned Performance

iTrader: (92)

If your looking for a base you might want to check out this tpis big mouth.
https://m.ebay.com/itm/tpi-big-mouth...QAAOSw7btawRHy

ULTM8Z

$600? Holy crap...

You'd REALLY want to have to retain TPI in order to spend that much money on that and put it on a 406.

Geez.. you could get a new Stealth Ram for ~$420 and get much better performance on that 406.

BadSS

I’d consider the Accel base the best “replacement” aftermarket TPI. However, towards the end, Accel was reboxing Edelbrocks (but the intakes had “Edelbrock” cast on them). The TPiS TPI base was made by Edelbrock but more expensive - I believe there were no internal casting differences but TPiS gasket matched them. The Edelbrock was the most economical at one point and not that far off in flow from the real Accel casting and if ported I don’t think there is much difference in flow. The Vortec bases from Edelbrock don’t flow much better than a stock base, so I’d stay clear of those and the Vortec based heads if you’re going to run a TPI.

If you feel comfortable porting the plenum, base and runners, the stock base and a set of SLPs are hard to beat for the money involved on a 350 with heads flowing up to 250cfm at cam lift. In your case, practically stealing the SuperRam runners and plenum, they would work out even better. If you have to pay someone to port the stock base, you’re probably better off patiently looking for an aftermarket base on one of the for sale forums. Folks on eBay tend to want a premium for the aftermarket bases now that they’re not making them anymore. Even forum members are holding out for a lot more than they would have sold them for a few years ago.

The StealthRam is hard to beat on a 383 or 406 – it’ll give you similar bottom end and midrange as a dual plane carbed intake, better midrange than a single plane, and almost as good top end as a single plane. As ULTM8Z eluded to, the SteathRam is definitely more economical (you could probably sell the SuperRam upper on eBay and break even). If you run a smaller fast rate of rise cam, you can get good vacuum and have more than enough low and midrange power to get by with moderate rear gearing (3.23s) and stall (2400-2600rpm). However, just playing around and not really worried about quarter mile times, a long/longer runner set is more fun and will give you the impression you’re a lot faster than you really are in normal play mode.

I’ve said a number of times, if I never planned to race the car, a ported stock base and SLP runners are hard to beat for the “fun factor” and money involved. If I did more street driving and only raced it occasionally, I’d go with a ported FIRST with moderate gearing and stall speed and a moderately sized cam – it’ll give you similar bottom end and play around factor as the ported TPI/SLP combo and almost as good top-end and ETs as a StealthRam (with same heads, cam, gearing and stall speed). If I was more concerned with racing and ETs, then I’d go with the StealthRam and a bigger cam, with more gearing (3.73s or more), and higher stall speed (3,200rpm or more). What intake you pick is really up to personal preference and what compromises you’re willing to make with the car.

I personally didn’t want to run a lot of gearing, stall speed, or cam and decided on doing a max ported FIRST with welded and siamesed runners on a 406 - I fully expect to make peak power in the 5800 rpm range. Doing so was a little costly and it takes a TON of work and time. I surely wouldn’t recommend anyone going this route unless they could do their own porting, but I was able to do so and it just fits with what I want to do with the car. However, the engine has a quick change timing cover, I practically stole a single plane EFI intake and Accel throttle body, and have a “single plane” cam sitting on the shelf,,, just in case I don’t think the FIRST “combo” cam handle some car show or cruise-in clown that really ticks me off – lol.

Abubaca

iTrader: (3)

I'm running a HEAVILY ported max effort stock base (by Darin Dochterman) cut/ported/rewelded SLP runners and ported plenum on a 383 built for the street. (cam and heads sized accordingly). With a TKO 600 and 3.27 it's an absolute beast! -up to about 5000. I can get it to 5500 if I try. It won't win me a race or bragging rights on the dyno....but it's what I want.

On a 406, I'd want at least a ported stock base. Lots of porting. ...for ME, I love the look of the classic TPI and Super Ram. I grew up watching these cars and the go fast parts for 'em. BUT.....for the money? Sell the SR at a profit and look at that Stealthram at least.

Drew

iTrader: (58)

Kinda looks like it's cracked too... IDK.

skipnsb

Thanks for the thoughts so far it looks like I will keep my eye out for an aftermarket base. Its going in a C4 Corvette, strictly street, and I thought I read that the Stealth and other available options would not fit under the hood. The 406 won't go in the car until next fall so I have time to look. Any ballpark estimate to get a top quality port/weld on a stocker? Remember this is a street toy. Skip

Vader

Well, going under the stock hood of a c4 will make for a height limit. Didn't know that before.

Tuned Performance

iTrader: (92)

I have heard the hsr will fit if the groves on the top are milled off.
Better off getting a mini ram.