A call to AFR would settle the porting issue. My bet the same casting so might just be load them on the CNC port and a fresh valve job and your on your way. Aren't there fairly cheap LT1 intakes floating around that have the distributor hole done? My be a low buck way to get you a bunch better.

 

the 180s can be ported, have you considered a converted LT1 intake ie the poormans mini? If youre putting boost to it work the runners over some and save a lot.
How much boost are you planning on running? know the L98s are 2 bolt mains. They can handle some but-

Wouldnt start changing anything due to a dyno sheet, take it to the track, how does it feel to you? Should run pretty strong.
That claimed 40hp will start where the TPI starts crapping out, not straight across the board.
What rearend gear do you have?

 

I’m planning on 6 lbs if I leave the short block stock. 12 psi if I go with forged parts.

 

I have an LT1 intake for sale right now, if you're interested. Ron is right that you could end up w/a $400 Miniram. That is good Bang For The Buck.

LT1 Intake

 

What do you guys do that have converted the TPI intake to the LT1 for thermostat relocation and dealing with head port matching (with reverse cooling on the LT1) and distributor location? Drilling holes and machining??

Just curious.

 

Most machine shops can weld it up, or David Frederick in the parts for sale secltion can do the whole thing.

 

What ^he said. I believe Dave Frederick charges ~$300 to convert it, so you buy one like mine and you're into a "mini ram" on the cheap.


.

 

Interesting!

I remember this debate on mini ram vs. LT1 intake. Nothing was proven but was interesting dialogue.

https://www.corvetteforum.com/forums...t1-intake.html

 

Thanks guys. If I decide to go forced induction I’ll put forged everything in the bottom end and run 12-15 psi.

 

It would be cool to see a side by side, for sure. I'd vote for the Mini Ram making more power...but on a ~300-350chp engine, not a lot. I don't think the diff would be more than 10. On an engine like TPI421's, rklesdriver or 383...that's where the money on a Miniram would be worth it, IMO.

 

Stock, L98's generate something like 200rwhp. That's + or - 10rwhp. So, the OP is asking about a 50hp gain with mods added. I understand the question of disappointment. Here are my thoughts:

Dyno: Didn't remember seeing a comment on the dyno itself. Different dynos read high/low. It's not THAT reliable unless you measured stock first (on the same dyno). Even then.

Heat: We're in summer. How much was heat a factor in the runs?

Porting: SLPs aren't much bigger than stock runners. Of all aftermarket options, they are smallest. Let's see how you ported them. If not a lot, that's my first vote for power left on the table.

Cam Orientation: How did you install the cam? Degree it?

Head Planing: You reduced the size of the 180's to 58cc(ish)? I did too...for the same reasons you probably did. Later, I learned this cuts down on flow...though (shrouding) though AFRs don't really have this problem. Probably didn't hurt but it's odd considering your goal to boost it. Seems you should have left them at factory 65cc.

Flow: AFR 180's don't have quite the low-lift numbers of the 195 which is as much a reason for choosing the larger head even WITH a long-tube build. Talk of head/intake mismatch isn't THAT big a deal. Again, 195's are better if top-end (track) speed is the goal. Best longtube 350 setup in this forum is member "TA" IMO. He made it to 325rwhp after stroking his similar 1990 setup. I didn't see his 350 hp number but he might have been 20rwhp better using similar heads. He used TPIS runners which I think are 15rwhp better than "stockish" SLP runners. They have 1/4" bigger tubes.

Injectors: Injectors are only a problem if they don't spray as good as new. More FP might help a bit but not a lot (if operating properly).

Mufflers/Exhaust: What size exhaust tubing? Are mufflers one step bigger than exhaust tubing (i.e., 3" with 2.5" tubing)?

Bottom line: You might have left 20rwhp on the table which have as much to do with intake porting as anything. Maybe the rest based on dyno, cam degree, injector performance (not size), and tuning. I wouldn't be surprised if a MR gave you that 40rwhp promised. Partly because you may not have an optimized longtube INTAKE setup though. Again, it seems odd you cut-down the 180s to stock bowl size if planning on boosting it. Guessing it's a few miles down the road? Porting (in) a longtube setup is everything.

 

Should be able to get what you want yes, they're good flowing 180 heads.

 

Yup, I guess I got dyslexia while typing.

 

If you look around, there are guys who cut open the SLP runners, cut/ground out the dividers, and then welded the outside back on. Thus reducing the runner length.

 

Possibly a silly question possibly not, what are the goals and budget? Without a goal and budget this can turn into a project that never ends. If something does not give what you think it should be meets the stated goal then a success rather than an endless quest that will never be done.

 

The goals are constantly evolving and the budget is not fixed. Had I known what I know now I probably would have done an ls swap.

 

 

 

If you want a 10 second car build a 9 second car add 20k at least to the budget and plan on maintenance travel and lots of seat time unless you race 9 second cars already. Needs a cage and back half at least and aftermarket electronics or carbs or a good turbo. Not a cheap date and yes everything you have done is money down the rabbit hole.