breakmyfootoff

Ok, here's the situation. I just bought a T-Trim, and I also just rebuilt my shortblock about 10,000 miles ago with forged 10.7 to SRP pistons. I can't rebuild my short block right now so I'm going to lower my compression with the heads which I need anyway. Lloyd said he can get the stock LT1 combustion chambers to 59 cc's which would bring the CR down to about 10.4 to 1. So here's the options, help me decide.

1. Lloyd Elliot LE2 heads with 8 PSI of intercooled boost on 10.4 to 1 compression and rebuild the short block later (or sooner if it breaks) for more boost.

OR

2. Trick Flow LT1 heads with 10 PSI of intercooled boost on 9.7 to 1 compression.

Which would make more power? Which would break sooner?

CoUnTryMuZiCZ28

I would go with the trick flow heads.. then have lloyd open those chambers up a bit.. then get the CR to about 9.5:1 or lower and run w/e boost you feel you need..

breakmyfootoff

Thats the direction I'm leaning to at this point, but I just don't have the funds available at this time to buy the trick flows and have Lloyd work them over as well. If I get the trick flows though, they will make their way to Lloyd eventually. I'll just have to run them as sold untill I can afford to send them to him for more work.

Thats one vote for the trick flows.

NC-LT1

Being a head porter I will tell you that Lloyd can work the stock LT1 castings to perfection, and a light bowl clean up on the trickflows will surpas them no problem in flow. your comparing apples to oranges here.. keep in mind the 170cc runners on stock castings are small compared to the 195cc runners on the as cast trickflows. with boost porting is important, but wnot nearly as important as volume.. remember volume will allow more airflow through the runner and to the cylinder.. especially with a T-trim charger pushing. the decks on the trickflows are thicker which is another obvious advantage, as cast a 62cc chamber will also help drop your static compression ratio.. so the scenario is as follows....

buy the trickflows and bolt them on.. likely when funds are available, you have a much better platform to start paying for portwork on..

(a) 195cc runners can be taken out to almost 210 by a good porter who is familiar with the castings....

(b) 62cc chambers can be further worked for better valve unshrouding, and larger volume to further drop compression

(c) the thicker deck will lend itself better for even clamping force to maintain a flat sealing surface with minimum deflection of the mating surfaces.

(d) the trickflows can be ordered bare for $875 bucks and flow ~250CFM out of the box.. Valves and springs and retainers can be upgraded personally for better parts then what comes standard from trickflow, and done cheaper then the money you'd be saving by purchasing bare castings.

(e) the valve seats are for 2.02 / 1.60 valves which means the throats are larger then the LT1 stock castings.. another hidden expense if you decide to push the stockers to the limits.

(f) you will be running NEW valve guides for more accurate clearance and operation, the decks will not need to be surfaced to true meaning if you port stockers, they really should be milled a few thousanths to ensure a true mate, this means thinning the deck and decreasing chamber volume.

(g) If I thought long and hard enough at it I could get through the alphabet with great reasons to go the trickflow route. but I thihnk the above mentioned pros will in the end far outweigh the cons.

not sure what the best flowing LT1 head "truly" flows, but when it comes to moving air.. and especially in supercharged or turbo charged applications... volume is king.. port velocity is not nearly as important as with naturally aspirated motors, however it does generally mean that the port is very efficient for its minimal volume.

like this.. they make "mandrel bent 2.5" pipe for exhaust.. and going to it over the crimped stock exhaust on C4 vettes is an advantage.. but in the end the guy with 3" exhaust is gonna make more power... when there is a driving force.. pressure.. volume is more important to be large then fine tuned smaller ports which will become a restriction when flowing air at well above the volumetric efficiency they were designed to work with.

hope this outlines a few points.. and I have heard great things from Lloyd's heads.. but in this instance.. I would say they are not the best suited for your application.

Chris

NC-LT1

Here is an example of ported Vs. Stock cast LT1 heads.. these heads made great power in their naturally aspirated applion where the smaller runners and great velocity added gobs of torque and flowed well at higher rev ranges.. these were around 185-190cc runner volume and if memory serves me.. flowed in the high 250's maybe low 260's they are pretty much maxxed out unless you wanna get extreme.. but then you dumping money to get volume from welding the roofs and raising the runner.. what you can buy as cast from trickflow. and I am a LT1 stocker casting supporter..lol its good business to port them.. but I'm trying to be honest and fair here on what will be best in the long run!

Port comparrison of LT1 castings.. ported and as cast

here is a dyno graph overlay of two NA 350ci C4 vettes, one is a hot cam and the other a 235/242 GTP6 cam.. bigger cam worked well in the higher rev range with the bigger ported LT4 castings, but the velocity in the runners at lower RPM stunted the torque numbers along with the bigger duration of the camshaft. with a blower.. which do you think would flow more air? both sets of heads were on personal cars, and EXTESIVELY ported. enjoy

dyno overlay of LT1 and LT4 heads, cams were different

Chris

breakmyfootoff

Awesome post, and great information. Thank you very much!