Typical, I noticed it as soon as you pointed it out!
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Typical, I noticed it as soon as you pointed it out!
Its fine, better than having a thread with no help or feedback! I am definitely here to learn.
Here are the details of the second to last pull, munched down a little to fit in the picture. Comparison HP is what you would typically see on a dynojet. Dyno Dynamics will not represent "Dynojet" power as a real hp number as they are very particular about accuracy.
https://farm5.staticflickr.com/4866/...57ecf3e8_c.jpg
Not sure I am following what you did with the timing. Did you alter the initial advance at the distributor or in the PCM? If you have the distributer at 10° and the Initial in PCM at 10° there is a net change of Zero. If you retard the initial at the distributer you retard the timing. If you reduce the value in the PCM you advance the timing. If you increase the value in the PCM you retard the timing.Quote:
Originally Posted by donf
You are running almost a full point leaner than I typically see these engines run strongest at on E10 gasoline. I shoot for 12:1 up until peak torque and lean out toward 12.6:1 at higher rpm.
Thorley Tri-Y headers woke my G-van and my Express van up compared to manifolds but I have a hard time believing 1.6 roller rockers and Tri-Y headers are giving me more than 30 HP and 50 ft/lbs to the wheels more than you made. Especially considering the 4L85E in the Express van. On E85 the Express van did 330 rwtq and 272 RWHP on a Dynojet.
Years ago my 8.8:1 compression 1-ton 350 with stock TBI heads, stock flat tappet cam, 1.6:1 rockers, edelbrock 3704 intake, 454 TBI on a 1" open center spacer and Thorley Tri-Y dyno leveled out at 300 rwtq and slighly over 200 hp.
Are you sure the thermal valve flap in the air cleaner is opening before you make the dyno pull?
What I did timing wise. The initial advance with the distributor is at 10 degrees and never changed. I set the initial advance on the chip to different settings. Because the definition includes the initial advance on the total timing calculation for the main timing table, you can bump the whole table up and down very quickly by just changing the initial advance offset. Correct? During a WOT run only a dozen or so cells are hit, but It can help find if your table in those areas are way off.
Random main timing table cell at 20 Initial Advance 10
Initial advance on chip 10
True advance on that cell in addition to the initial timing 10 Total is 20
Random main timing table cell at 20 Initial Advance 10
Initial advance on chip 5
True advance on that cell in addition to the initial timing 15, total is now 25
The air cleaner is a black 14x3 from summit. I still have the stock 3" ring that I think may be a restriction, but haven't looked into it yet. I am not that disappointed. I actually gained a lot torque wise and its felt with a big van. It's basically stock vortec style heads with the sharp edges below the seat knocked off, with an almost stock roller cam with tighter LC and a tbi intake. So really I was not expecting more than 200 at the wheels. It's not done, I can keep messing with it as time allows, but it's good enough to drive now.
I know there are variances between Dyno's but a few years ago I made 196HP RWHP with a basically stock LO5 TBI 350 in my van, it only had headers, a 3" single exhaust system, a salad bowl on the TBI and 13PSI fuel pressure.
I also ditched the stock fan for twin electric fans but that was more for cooling rather than HP but it would have helped.
You are potentially leaving a few horsepower on the table with the 13:1 AFR, I'd be seeing what it could do in the 12:4-12.8 range.
The stock ring will be a little bit of a restriction, that's why the salad bowl conversion helps improve air flow into the throttle body.
What do you have for an exhaust?
Thanks for the feedback, for the exhaust see Post #77Quote:
Originally Posted by Kitch
The choker ring of death as I call it. I used a hypertech powerbowl back in the day but I think they have been discontinued. Could make something equal out of a HVAC part or a stainless mixing bowl. Cut the base of the air cleaner to match.Quote:
Originally Posted by donf
Something still seems off. Did you use standard roller lifters? What did you lash them at? On normal small block stuff I run about 1/4 turn past Zero lash which I find with a running adjustment. Valve lash that is too tight will cost you torque in my experience.
I have seen that cam and Vortec heads make 320 hp and 400 ft/lbs of torque with a 650cfm carb, performer intake and 1 5/8" long tube headers. A GM 330 hp 350 HO still made 320 hp through 2 1/4" cast iron manifolds and 337 hp with 1 5/8" long tubes. Given those results I would expect you to still see an honest 280 hp with log style manifolds and TBI. At 20% loss that is still 225 hp.
My Vortec 350 with the same cam was floating the valves wildly above 4,500 rpm and running with the stock spider injection manifold still put down 229 rwhp and 303 rwtq. Stock vortec heads cut for 2.02/1.60 valves which only marginally increased the flow numbers at lower lifts. 1.6 rockers and tri-ys. 2md gear pull through a locked 85E and 9.5" 14-bolt. Also had a massive duramax mechanical fan on it at the time.
I am not knocking your results at all just trying to figure out where your missing power is hiding. The reringed 250K mile 305 Vortec in my 99 Tahoe put down more torque than your 350 is with a 218/218 @ .050 flat tappet cam.
duplicate...
You are correct on the timing. You are able to quickly offset the whole curve by altering the initial value in the chip.
I think the biggest shock to me is the stock swirl port head, stock TBI cam HD 8600 gvw 350 engine I ran years ago with its huge 18cc dished pistons made the same HP and alot more torque. It also held in strong until well over 4,500 rpm. I attached the dyno runs above of both that engine and the 350 Vortec in the Express before I fixed the valve spring issue and retuned it for E85. Just swapping valve springs to the LS6 beehives and Comp 787 retainers put me at 257 rwhp and 310 rwtq compared to the 229/303. Peak torque moved down in RPM and peak hp moved up in RPM. It also made that earthquake of a dyno sheet much smoother overall. Valve springs also fixed that 30 hp drop in 200 rpm and made it an actual smooth curve until the 5,600 rpm fuel kill. I was still making 240 rwhp at 5,600 after. I tested the old springs and only had 55# on the seat and 150 open! Had worn out hecho en mexico vortec springs in only 50K miles. LS6 springs were like 90# on the seat and 260# open.
Also a further discrepency I see is the fact the 300 HP marine TBI Vortec engines used the same cam and a GMPP Vortec TBI like manifold except without EGR provisions with 2" TB openings and 454 TBI unit. With restrictive marine wet exhaust manifolds they were NET rated at 300 hp and 370 tq. Even at 300 hp you are barely being restricted by the stock small block TBI unit as it only becomes a slight restriction in stock form in the 275 hp range and is capable of 325+ before a 454 TBI unit becomes noticeably stronger.
I appreciate the Ideas. I will not be upset if it makes more hp than I expected. I set the roller lifters the standard way, 1/2 turn preload. Not running. I have not had problems setting them that way before, but I can check them again. I have upgraded springs so it could go higher, I just don't see the need. I still think that there is something wrong with the spark advance as its still not matching the table in tuner pro, but from what I did today, it did not seem to make a lot of difference at WOT. It made less HP with 10 degrees tacked on. Filling in the altitude scalar from 0 to 9.8 sure made a big loss though that was easy to see. Jegs has a house brand salad bowl, but I think I will do a run with no ring just to see if that's a big problem.
One thing to keep in mind is you're comparing dyno dynamics numbers to dynojet. Even in NASA (the car racing association, not space travel) they take the DD and Mustang numbers both hp and torque and multiply them by 1.1 to get in the ballpark for DynoJet sometimes it's even more on top of that. The numbers I have were corrected (reduced) by 3% for weather it says that at the top of the sheet. Dynojet has inflated numbers because they think bragging rights = sales. I will be happy to find more hp, but the measuring stick has to be close before you compare.
I would definately try a 1/4 turn running since it would not take long to do. It would be interesting to see if there is a difference and how much of a difference there might be. I had a blueprinted .040" over flat top piston 305 with 081 centerbolt TPI heads, a L69 cam, 1.6:1 rockers, swapped to TBI with those same Thorley headers years ago go from 140 hp and 220 tq to 193 hp and 282 tq on a Mustang dyno going from a static adjusted 1 turn to a running adjusted 1/4 turn. This was after being disgusted by building an engine that made less power than the stock 250K mile 305 that I had previously swapped to TBI. The stock LE9 engine with a 204/214 cam had made 165 hp and 250 tq. After beating my head on the wall and finally having an instructer at the trade school I attended with 30+ years experience building race motors suggest trying it. It actually made 181/268 from the valve adjustment alone but the afr was in the mid 13s after. Burned a chip with 10% added to the VE tables and the AFR went to the mid 12s. The AFR was spot on at 12.5 before the change. After thinking about it for a while it made sense that doing what I had done gave me a more accurate adjustment of the rockers, less chance for lifter pump up and overall more consistant valve lift and valve timing.Quote:
Originally Posted by donf
Also don't write off a powerbowl if your open TBI test results in no gains or a loss. IMO the TBI needs something to help straighten the airflow entering it. The choker ring does it to some effect but I feel the parabolic shape of the bowl does it even better.
I know there is a difference. I ran my Titan on a Mustang dyno. It put down 296 rwhp and 388 rwtq. I put it on the same Dynojet and saw 330 rwhp and 396 rwtq. The 1.1 conversion is probably fairly accurate at the HP peak, but in atleast that instance the torque difference was much less.Quote:
Originally Posted by donf