Sorry not able to test between the two right now on a dyno.
The car is down for fresh rings,valvesprings, and the basic winter freshing.
The larger duct had not been made nor ever ran on my old LT1 combo that the small duct was created with.
Both Lt1's were the same cubes and 12.3 :1 but camshafts are worlds apart
Have a few months of down time on my hands.

But as I stated all ready the larger duct showed a improvement in map readings over the small duct. I had a two percent higher reading at wot, this is the only comparinson info I have.

 

Sorry, catching up…

I'm not sure I'm following… what's wrong with it in the middle of the port? Unless you mean in the middle of the intake runner (I would imagine that the single plane runners sit up higher then the LTx runners.

Anyone have a take on what effect the curved runners used on most single plane runners has on air/fuel distribution on an FI SBC layout? I would imagine that each of the paired runners would see slightly different flow since the airflow would tend to like to 'stick' to the outside of the turn, and the outside runner of the pair would basically get the airflow deposited on the fast side of the port where the inside runners would get it dumped along the slow side (against the dividing wall), possibly even messing with flow and swirl…

Care to elaborate here? I've been thinking about this and I could come up with a lot of things to change to optimize for the intake manifold change, but I'm not sure that the cam was really one of them. I would imagine that it would fatten up the midrange a bit, the end result being that you could get the basic response with a wider LSA, but I'm not sure that I would run one just because of that... So what would you change and why?

 

Thanks Jeff.....one last question.....is there any 4bbl TB available that will allow one to retain their cruise control?

Thanks again
Jason

 

Couldn't one just fab up an extra "nub" on the throttle cable arm for the cruise cable?

A.

 

Ya got me on the cruise stuff ... sorry.
would seem like you would mount the cable in a manor that would pull from the oppsit [sp?] end of the arm where the throttle cable pulls from with the cruise cable routing on the front side of the TB. Just a idea, I'll look in the TCI stuff tomorrow at work and see what they have for brackets.

 

Jeff, what is the hight from top to bottom of your 4 bbl, not including the arm?

Reason i ask is the one from forcedefi that im looking at is 2" high. So i want to make sure yours wasnt smaller when you were refering to the duct clearing the hood etc.

 

Would this provide a worthwhile gain for a FI car?

BTW I've seen that elbow in person and it's BADASS!

 

I have a question for whom ever has done a Super Vic intake conversion:

1.Is it possible to use the Edelbroch Super Victor intake with AFR heads? I was told that if the AFR heads have the fuel injection LT manifold bolt pattern this would not allow the use of the Victor and thats because when the LT bolt pattern is redrilled into the Victor manifold the intake manifold bolts would be to close to the manifold intake runner and or would be drilling into the side of the runner?

The area I'm talking about would be where the two middle bolts go, basically in between the manifold runners when two runners split to 1,3 and the other two split to 5,7 cylinder, the area in between. I was told the heads would have to be drilled and taped?

Is this true?

I know of one person who picked up 50hp on the top end switching from LT4 FI manifold to the Victor and a large throttle body! Others are seeing at least 20+hp increase with this switch. These engines where all 396ci or larger with good size cams over .600 lift.

Thanks for the info!

 

The main advantage of this setup is that you get much better intake pulse tuning from the added runner length. In a FI application you are not going to gain anything in terms of volumetric efficiency so it's basically a big waste of time and money on a FI car.

Actually no. To elaborate on this more would mean that I would have to tell which way to go on the cam specs and that's going to give more of the specs away. The cam is the BIGGEST change you need to make going from a LT1 to a single plane intake. The only way I would elaborate more is with a cam and valvetrain purchase. Then the specs and reasoning is free.

Bret

 

In most circles FI refers to fuel injection (and I think that's what he meant in his original question, but I could be wrong). Reading your response I can only guess that you used FI to mean forced induction.

Based on that, I'd say that your response is true for a race car that sees boost ALL the time, probably in excess of 8psi or so, but not true in a street car that probably spends most of it's life NA and only sees boost when someone is doing "something stupid." To really give an accurate response you'd have to give some consideration to ram tuning, harmonic tuning (which harmonic are you actually hitting) and the rest of the chassis, as well as how it is going to be used.

Are you serious? (have humorous, half serious…)

Seems like somewhat of a strange response to a question that you could get a reasonable answer to by reading one of half a dozen books. More then anything I was trying to learn what camp you fall in WRT to what's important in this case (file it away for future discussions, like in the above response, it's pretty obvious that you're looking at things from a race only viewpoint, but the more I understand about your viewpoint behind your thoughts…). The second thing that I was trying to figure out is why I happened to be brainfarting on what I would do in that case (mostly because I don't seem to have a firm handle on what the desired outcome for this is, whether the desired effect is to accentuate the changes in tuning… actually I think I answered this second part for myself in trying to figure out how to word this…)

 

I'm quite sure Jim "birdy2000" was looking for "forced Induction" benifits with a singleplane vrs lt1/lt4. Jim is a forced induction LT1 with arf heads.

 

Yes, sorry for the confusion. Was referring to Forced Induction. Everyone over in that forum refers to it as FI, so that's what I'm used to. I guess I took it for granted since we were referring to the LT1 and since my sig clearly states that my car is a forced induction car.

 

Hey Jeff, I'm still waiting on a reply to my question above ^

 

NA is NA, EFI or carbed the same benefits will be the same.

The point you don't get about the FI setup is that NA applications work solely on a negative pressure side where the motor is sucking the air in. Once you go to a blower you are at least at a even pressure or postive pressure, in that situation the longer runner lengths are not going to help because the pressure will not allow the manifold tuning to take place.

Did it look like I was joking? Selling camshafts pays the bills, giving you free advice doesn't. Pleanty of other people buy camshafts from me and understand that.

I might like look like an *** to you for saying that, but if you can go pick your own cam out from just reading books then do it. If it's not obvious to you that the camshaft needs to be changed going from a LT1 intake to a single plane then it really makes me wonder how you are going to even get close. (Don't read this as being nasty)

I don't look at it from a race only viewpoint. Race or street every motor has advantages and disadvantages you have to use in camshaft selection. Street motors have a wider RPM band to play in where a race motor has a higher RPM band to play in you have to consider that. In essence the same pricinpals apply.

You could probably do a search on me and camshafts in the Adv Tech Forum and see where I come from regaurding camshafts.

One thing people don't take into accout on a camshaft in a LT1 is the intake manifold. Thru trial and error they get pretty close to what's going on, but you could really gain alot more if you understood the lack of intake pulse tuning that the LT1 intake has.

Anyways, if you have th optimum camshaft on a LT1 intake setup it's not going to be optimum when you go to a single plane because the cam is not going to work well with the intake tuning pluses at various RPM.

Bret

 

I'm not sure that I'm seeing the point you're making with that statemenet, but I would argue that for the most part they are the same except the way that they deal with turns and surface finishes.

It's not that I "don't get don't get about the FI setup is that NA applications work solely on a negative pressure side where the motor is sucking the air in…" it's that I've seen otherwise, harmonic and ram tuning still work with positive pressure. Even with boost masking the shape of the power curve, you can still see the effect of harmonic and ram tuning on the power curve. You're just choosing to ignore that (and there are valid reasons to do so). This is a great example of why I was asking the second question (learning your reasoning for the response you gave)....

In a boosted application I would stay away from harmonic tuning for the lower harmonics (since that usually requires LONG runners which will be a restriction under boost), but ram tuning works well. In a high boost/race application I would agree with you since you can get a greater effect on the power curve by running a few more lbs of boost then you would from the time/money spend on intake tuning. If you're detonation limited anyway, it doesn't make a difference if you fill the cylinders/create cylinder pressure using intake tuning or boost.

The fact is that the correct answer here is what is your application and what are the limitations that you're working under? If you're running methanol and are allowed 45psi boost, then skip the runners, they end up just being a restriction. If you're running 10psi, well, you're in a different world.

That's wonderful, but the people that are going to come to you to spec out a camshaft don't really care what you say here, they want to know what you would recommend for their specific application. It's doubtful that someone that would come to you for a camshaft would even be reading here, I'd bet that most people that read here would choose their own camshaft whether they know what difference and earlier EVO (or any timing event) has on their power curve or not. As far as I can tell most people never get that far with their understanding of camshafts and just care about durations and the relative location of the lobes (LSA) and decide that they know enough to choose their own. If the people that would come to you were reading here did see an intelligent response (that they would most likely not understand the full ramifications of anyway) that would just reinforce that 'this guy knows what he's talking about' and make them more likely to call you the next day.

You're treating this whole thing like someone went "uh, I've got a 355, X heads, I want to run these headers, this intake…" and bitching that you didn't tell them "have a cam ground with xxx lobe and yyy lobe…" No one is asking that question. I could care less what the actual profile would be that you would select. I was curious what YOUR changes and considerations/reasoning would be in going from essentially an 'untuned' intake to one that will have both ram tuning and a harmonic tuning effect on the engine.

I'm not sure that I'm being clear here but what you seem to be acting like everyone here asking a specific question is trying to rip you off. The simple fact is that I asked the original question because I'm looking for someone that might be looking at this differently then I am and am wondering what angle he is looking at it from. It's not like I'm building this engine with this intake… it's a simple academic exercise. More then anything else, I was just hoping that you would say something that I haven't thought of before that may spark some thoughts of avenues that I may want to look into. I may agree with what you say, I may not. You may agree with what I say and you may not, but there is the slight chance that I'll say something that will get you thinking about different approaches, even if you hate what I say and don't think it would ever work.

If you don't like it then fine, lets not have a discussion on how intake tuning effects cam event timing. Frankly, I'm surprised since I believe a year or 2 ago you or Jon made a statement about how unpleasant boards like this get when people start acting like they know some secret that no one else knows or will ever find out and no one throws any real ideas out. The speculation, playing "what if" and exploration of ideas die and it stops being advanced tech and becomes "engine basics" and "if you want it right just buy X" (basically a product review).