Over the winter I took off my fully ported supperram and replaced it with a LT-1 intake that I modified and ported to fit my 406 Gen I SBC. (This was the only change that I made to the engine, and drivetrain, everything else is still the same as in my sig.) My initial feeling was that it still had good low end power and better top end power then the supperam but it was hard to tell because of the time span between driving the car with both intakes. (With street tires it was impossible to get traction in first gear with either intake.) Since I wanted to know how the two intakes effected the power curve and what the differences were, I took the car to the dyno today and tuned the combination. The final results were that the LT-1 inake on my engine combination did not give up any low end power to the supperam and the LT-1 intake made quite a bit more top end power. My best results with the superram inake were 437 RWTQ at 4000 RPM and 405 RWHP at 5400, the best results for the LT-1 intake were 469 RWTQ at 2900 RPM and 452 RWHP at 6400 RPM. These results were with the torque convertor locked so I could see what the engine was doing without being influenced by the torque convertor.
When you compare the graphs of the superam to the LT-1 intake you notice a drastic difference in their curves. The supperam curve looks like the typical bell curve with a big rise in torque and then a steep dropoff in torque, the LT-1 intake has a very flat torque curve. The surprising thing about this test on my engine combination is that the LT-1 itake never trailed the superram intake in power anywhere along the curve. Between 4000 RPM and 5000 RPM the curves between the two intakes are almost identical but before and after that the LT-1 intake is making more power.
I had expected more low end power with the superram in comparison to the LT-1 intake and more upper RPM power with the LT-1 inake in comparison to the LT-1 intake. What I ended up with was more low end power with the LT-1 intake, equal did range power with both intakes, and more top end power with the LT-1 intake.

Tomorrow I am going to the strip to see if I can better my best run with the Supperam intake.

One side note the LT-1 inake is much easier to tune the idle with. My superram was very duficult to tune for a steady idle at 850 RPM. The Lt-1 inake was very easy to tune for a 850 RPM idle and it is rock steady.

 

WOW, that's a nice gain!!! Anxious to see the track results.

 

452rwhp with an intake change, a gain of 47 hp, I can't say I'm surprised. Looks like you'll be in the 10's with traction.

P.S. I forgot to buy milk at Pick and Save the last time I was shopping, I wonder why?

 

Are the torque figures switched? They don't seem correct.
Scott

 

Keep us updated Brian. That's for the article.

 

Great information,
Time to change your signature.

 

something it's strange...
Do you confirm that the MAX torque with the Lt1 intake is at 2,900 rpm?
And that the MAX torque on the SR is at 4,000 an it's 32 ftlb less than the LT1?
If all is confirmed and the two dyno comparisons are comparable ...why I'm so stupid to use a Fully ported SR on my car?
-Beppe-

 

The numbers are not switched, with the LT-1 intake the engine hit max torque on 9 different dyno runs at 2900 RPM to 3000 RPM. I am not sure why this was happening, maybe my combination of high flow high flow heads and cam were being restricted by the superram. The supperam and LT-1 intake made the same power bewteen 4000 RPM and 5000 RPM.

My guess on why the LT-1 intake was better then the Supperam on my engine is that the supperam was mismatched to my engine combination. My engine has heads and cam that can support HP at 6500 RPM. If my engine had heads and cam that were designed to peak at 5500 RPM to 6000 RPM I believe the Superram would have been the better intake.

I still have a 355 with the supperam on it and I am not going to change it because I believe the supperram works better over that engines power band.

 

Are you still using 23 degree Trick Flow Heads (195 cc) and ZZX cam?
..Or are these in the 355?
-Beppe-

 

I am still using the ZZX cam and TFS 195 heads but the heads have been ported out to 218 CC and flow 311 CFM at .600 lift.

 

It looks like the LT1(MR) is the way to go. You thinking about selling the SR now?

Great info Brian. Keep us updated on the track times. Brian, I am still doing the 383 MR/AFR combo, but it wont be in tell later on in the year to let you know. I am glad I sold my SR, and kept with the MR. 6400 rpm's with a 406 is very nice. congrats!

Brian, Can you make a comparision between the 2 intakes stateing the 1/4 miles times/tuneable etc???

 

So you don't lose all your torque with an LT1/Mini Ram?

 

No need to laugh. The big cubes dont need long runners to make amazing torque.

 

Do you have any way to post the graphs? I've been mulling over intakes for my mild 383 for months now, so this is very interesting...

 

Not only that, but on the smaller 350's, the miniram will make more torque than a long tube runner from off idle to ~2700 rpms. After that, the long tube runner design will typically make more torque from ~3K to ~4K rpms....maybe 15 lbs or so.

I dont rev my motor above 2700 rpms on the street. No low end torque missed here.

 

Hey Brian, I agree with your assessment on the head/cam setup being part of the results, also, interesting tune info, I would have thought the SR would have been easier to get to idle than the LT1 intake

I will be going to the dyno to compare my Miniram numbers to the Stealth Ram in a week or two, once Alvin looks at my last log. My clutch is working properly now so I should be good to go

Picking up that much HP does not surprise me, but the TQ gain is interesting for sure congrats on this mod for sure

I'm anxious to hear see your track ET comparison...

 

That is such a great point to be made especially since most threads are SR vs MR on an already laid out combo. They really do require two different engines to be maximized.

This is a great example of that, and to that end, the track results will be interesting. I remember a couple SR 406's going 10.9ish. The comparo should be neat.

Great motor

 

Congrats on the gains! Geez! nearly 50HP gain at the wheels

Where are you going to run on Sunday? Looks like it will be a hot one out so best of luck to you. I hope you snag a 10.

 

Nice to see some hard facts instead of the usual SOTP opinions in the GREAT INTAKE debate.(ongoing)

Proves the LT1 conversion is still a viable option for those of us L98 owners on a budget .

 

What was the outcome?